Arsenal manager Arsene Wenger feels Manchester United's shock exit from the FA Cup may give their rivals a slight advantage in the quest for European glory.
The Gunners booked a place in the fourth round, where they will face Stoke, after coming from behind to win 2-1 at West Ham.
Earlier in the day, a much-changed United had been beaten at home by Coca-Cola League One leaders Leeds.
Wenger believes with the domestic and European fixtures piling up towards February, that extra rest for Sir Alex Ferguson's men could prove crucial.
"Manchester United won't gain a great advantage in the Premier League, it is more with the Champions League that the FA Cup is conflicting," said Wenger.
"The fifth round is just before a Champions League game and before that we play a lot in midweek.
"But at the moment, I don't think Manchester United have gained an advantage in the title race."
Wenger openly admits he would like to strengthen his squad - without Holland striker Robin van Persie to a long-term injury - as they look to compete on all fronts, but remains unsure just what the January sales will bring.
He said: "As many people say - I have the money, I have the desire, but I have not the players.
"I do not know what will happen [in the transfer window generally].
"Basically, it depends how the big guns - Manchester City and Chelsea - will move.
"Where will they buy? If they buy from English clubs, the market will be busy.
"If they do not buy from English clubs, I think the market will be very quiet because there is not a lot of money around."
With one eye on Wednesday night's crucial Barclays Premier League clash against Bolton, when Arsenal could close the gap on leaders Chelsea to just one point, Wenger made five changes to his starting XI, giving games to reserve keeper Lukasz Fabianski, youngsters Carlos Vela, Fran Merida and Luke Wilshere along with veteran defender Mikael Silvestre.
West Ham took the lead in first-half stoppage time when Alessandro Diamanti beat the offside trap.
However, after Wenger had sent on Abou Diaby and Samir Nasri just after the hour, the visitors got themselves back in the tie through the outstanding Aaron Ramsey before Eduardo's looping header completed the turnaround with seven minutes left.
Wenger said: "We had a very difficult first half, against a West Ham side who were committed and got caught on the break.
"In the second half we played at a higher tempo and could make the difference in the final 20 minutes."
Ramsey turned 19 on Boxing Day.
With Alex Song set to join Cameroon at the African Nations Cup, and captain Cesc Fabregas sidelined by a hamstring problem, the Wales midfielder looks set for a sustained run in the side.
"He improves from game to game. I set him a target at the start of the season to play between 15 and 20 games," said Wenger.
"It looks like he will get that very quickly."