Louis van Gaal looks set to speak to Jose Mourinho over his claim that signing Luke Shaw would have "killed" Chelsea.
Shaw became the fourth-most expensive defender in history this summer when he signed for Manchester United for an initial fee of £27million.
Chelsea, who Shaw supported as a youngster, were interested in the 19-year-old, but Mourinho revealed he pulled out of a bid to sign the player due to his wage demands.
The Chelsea manager claimed Shaw's reported wages of around £100,000 a week were way too large for a player who only made his Premier League debut in November 2012.
"If we pay to a 19-year-old boy what we were being asked for, to sign Luke Shaw, we are dead," Mourinho was quoted as saying in several national newspapers.
Manchester United: Potential summer transfer targets
Manchester United: Potential summer transfer targets
1/19 Arturo Vidal
The Juventus midfielder is among United's top targets this summer, particularly after impressing for Chile at the World Cup. Having helped his current team secure the Serie A title, Juventus aren't keen on letting him go.
2/19 Marco Reus
Rumoured to be near the top of United's target list, a possible swap deal involving cash and Shinji Kagawa has been mentioned. The Borussia Dortmund player would not be a cheap acquisition, especially given his recent declaration that he wants to stay at Dortmund next season
3/19 Arda Turan
Former manager David Moyes had been seen watching Turan, though his dismissal put a doubt over whether United were still interested. The winger's agent claims an offer has been made, so is the Atletico Madrid winger on his way to Old Trafford?
4/19 Arjen Robben
The Bayern Munich winger has said Van Gaal has offered him a place at Old Trafford if he wants it. Currently he's happy to stay where he is, but things can quickly change.
5/19 Claudio Marchisio
With Paul Pogba highly unlikely to be prised away from Juventus, United's attention could turn to team-mate Claudio Marchisio. The Italian international would provide some class and experience.
6/19 Mats Hummels
With defensive reinforcements high on United's list of priorities, Borussia Dortmund's Mats Hummels has unsurprisingly been linked with a move to Old Trafford. The German has been earmarked as the ideal replacement for the now-departed Rio Ferdinand and after his impressive showing at the World Cup, he's even more desirable.
7/19 Raphael Varane
Raphael Varane has already snubbed United once in his career, opting instead to join Real Madrid. It would surely take a big offer to prise the classy defender away now.
8/19 Seamus Coleman
Reportedly already the subject of a £15m bid, Seamus Coleman could be the man being lined up as the answer to United's problems at right-back.
9/19 William Carvalho
The Sporting Lisbon midfielder has reportedly been watched 15 times by Manchester United, although the £29m asking price could prove a stumbling block. The Portugal international has also been linked with Arsenal.
10/19 Xherdan Shaqiri
Bayern Munich winger Xherdan Shaqiri has struggled to force his way into the first team at the Allianz Arena and could be a target for United as well as rivals Liverpool. His impressive displays for Switzerland this summer could make it harder to prise him away.
11/19 Alex Song
Barcelona are understood to be ready to let the former Arsenal player leave this summer. Could provide some strength to United's midfield. Could also bring embarrassment judging by his behaviour at the World Cup.
12/19 Fabio Coentrao
Supposedly came within hours of signing in January, the Portuguese left back could be brought in to provide back-up to Luke Shaw.
13/19 Julian Draxler
A long time Arsenal target, United are reportedly interested in pinching the young German with a bumper offer. Seems unlikely though. Arsenal also strongly interested.
14/19 Sami Khedira
The Germany international is reportedly being pursued by a host of sides, and United might be wise to get in the mix as they look to add some quality to a fairly feeble looking midfield. Real Madrid appear open to letting him go with the 27-year-old having just one year left on his contract. Arsenal and Chelsea are among the others keen on signing the World Cup winner.
15/19 Edinson Cavani
The Uruguayan hitman would prove pricey and tricky to snatch away from PSG and it seems unlikely United have enough to offer him.
16/19 Luciano Vietto
The Racing Club youngster has been impressing in Argentina for some time although a move directly to United would be something of a surprise.
17/19 Santiago Arias
Should a move for Seamus Coleman fail, PSV defender Arias is reportedly being lined up by United. Played for Colombia throughout the group stage of the World Cup.
18/19 Miralem Pjanic
Rumoured to part of a joint bid including teammate Benatia, the Bosnian midfielder is reportedly another on United's large hit list.
19/19 Kevin Strootman
Van Gaal knows Strootman well from working with him in the Netherlands set-up and has indicated he is interested. Roma are reluctant to sell whilst his recovery from a knee injury may prove a stumbling block.
"We would have killed our stability with financial fair play and killed the stability in our dressing room, because when you pay that much to a 19-year-old kid - a good player, fantastic player - but when you pay that amount of money, the next day, we would have had players knocking on our door.
"They would have been saying, 'How is it possible I play 200 games for this club, won this and that, yet a 19-year-old comes here and gets more money than I get?"'
Van Gaal refused to get drawn into a public war of words with Mourinho - a former protege of his at Barcelona - but it appears he will discuss the matter privately with the Portuguese.
"I don't think I have to discuss things in the media, it's better to discuss it with Jose," he said.
Mourinho recently spoke about how he was looking forward to coming up against the man he assisted at Barcelona for three years.
The Chelsea boss said earlier this week that there is a "fantastic relation" between the pair, but that could be tested further this season if the Portuguese criticises Van Gaal's new charges.
After signing Diego Costa, Filipe Luis, Cesc Fabregas and Didier Drogba, Mourinho is happy with his squad ahead of the new season.
That is not the case for Van Gaal though. The Dutchman is looking to sign at least one centre-back before the transfer window shuts and another midfielder.
One of those on Van Gaal's shortlist is Kevin Strootman. Roma coach Rudi Garcia insisted on Friday that the Holland midfielder would not leave the Italian club this summer.
But Van Gaal refused to rule out the possibility of signing the 24-year-old once he recovers from the serious knee injury he suffered in March.
"We have to wait and see how he comes back from his injury, he has been out for over six months," Van Gaal said when asked about reports he was interested in signing his compatriot.
Strootman has been left in Boston, where Roma played Liverpool earlier this week, to recover from his injury, so the Dutchman will not face United in Saturday's friendly in Denver.
Van Gaal, who admitted he has been unimpressed with some of United's players in training, was laying down the law to his squad on the eve of the match.
The Dutchman gave Chris Smalling a dressing down during an open training session at the Sports Authority Field and he seemed extremely unimpressed by a select group who continued to miss the target from set-pieces.
Off the pitch Van Gaal has been making his presence felt too, demanding water breaks during Saturday's match, which is due to be played in the 33 degree Colorado heat.
"It is unbelievable that we play at 2pm," said Van Gaal, who criticised FIFA for making Holland play Mexico on a blistering afternoon in Fortaleza during the World Cup.
"We have to adapt to the situation.
"All the players will play 45 minutes apart from Tom Cleverley and Tyler Blackett.
"For these players it is very hard.
"I hope to have a pause for a drink also. I shall convince the referee, like it did in Fortaleza. It was the first time they had a drinks break at the World Cup. Mostly they listen."
Cleverley lost his place in England's World Cup squad after a poor season under David Moyes, but hopes to excel this term.
The midfielder, who got two hefty pats on the back from Van Gaal as he sat by him during the pre-match press conference, thinks he can benefit from playing in the manager's new 3-5-2 formation.
"I watched Holland in the World Cup and I think I can be his type of player," Cleverley said.
"I have to show that in training and most importantly in the games. I think there is a place for me. I have to prove that."
Rafael will miss the friendly, which is part of the International Champions Cup, after he hobbled off in training with what looked like a groin injury.