The Portuguese star opened his account shortly before half-time but Newcastle threatened to spoil his United comeback following an equaliser from Javier Manquillo.
But Ronaldo struck once more after the break to double his tally and re-establish United’s lead, in front of a raucous home crowd at Old Trafford.
Bruno Fernandes and Jesse Lingard made the scoreline more comfortable for the hosts late on, but the afternoon was all about one man as Ronaldo marked his return to English football with three points.
Here are five things we learned.
Cristiano Ronaldo’s perfect return
Of course, it had to be him. Manchester United were heading into half-time looking at a frustrating stalemate against Newcastle before Cristiano Ronaldo marked his return to Premier League with the breakthrough goal, to the delight of a frenzied home crowd at Old Trafford.
It was the moment they had been waiting for, and the fact that it was a tap-in from two yards following a mistake from Newcastle goalkeeper Freddie Woodman, rather than a stunning strike or a towering trademark header, did not seem to matter.
United were then looking at an uncomfortable afternoon when the visitors pulled one back, but Ronaldo’s response was emphatic as he fired a shot through the Newcastle goalkeeper’s legs to re-establish his side’s lead.
The goals was illustrative of the changes to Ronaldo’s game since he left Old Trafford 12 years ago. Sure, there are still the odd flashes of the tricky winger that enthralled fans on his first spell in the Premier League, such as when he received the ball into the box and beat his man with a stepover before shooting at goal, but Ronaldo is a pure goalscorer now - and could be the one United need to take them to the next level under Ole Gunnar Solskjaer.
After a bright start to his United debut, Ronaldo saw relatively little of the ball in the final 15 minutes of the opening half and throughout the second period. But it didn’t matter. He still provided the crucial goals to spark his side’s 4-1 win, and mark a sensational return to the Premier League.
Partnership with Fernandes
There were questions before Cristiano Ronaldo’s debut surrounding the impact it might have on Bruno Fernandes, given some of the playmaker’s struggles when playing in Ronaldo’s shadow for the Portugal national team.
The link-up appeared to be there from the first few minutes at Old Trafford, however, with Fernandes almost playing in Ronaldo with a chipped pass early on. A Ronaldo flick into Fernandes’ path also illustrated that they were on the same wavelength, with Fernandes looking for Ronaldo’s runs whenever he got on the ball.
Fernandes showed that he will continue to attempt the spectacular, despite Ronaldo’s presence in the team, illustrated by a stunning goal from 25 yards to put United 3-1 in front.
This wasn’t Fernandes’ most influential display by any means and indeed the win will be viewed as all about Ronaldo, but Fernandes’ celebration and overall display suggested that he is motivated to ensure that this remains his team.
Paul Pogba and United’s midfield balance
United were sparkling in attack at times, particularly when the game opened up in the second half, but questions remain over the defensive side of their play - particularly the balance of their midfield.
Paul Pogba’s was perhaps United’s best player in their first month of the season but has now been played in a midfield two in his last two games. He was moved into a midfield two for the trip to Wolves following the injury to Scott McTominay and alongside Fred, Pogba was not at his influential best at the Molineux as United struggled to deal with Wolves’ counter attacks, and was deployed in the same position here.
The result was largely the same. United struggled to deal with Newcastle’s counter-attacks and it was from that phase of play that brought Newcastle’s equaliser in the second half. It was also interesting to note that Pogba looked to keep things simple against Newcastle, with the hosts enjoying the vast majority of possession at Old Trafford, and playing in that position does not seem to bring the best out of the Frenchman.
United will need to find the right balance over the next few weeks - but it does not seem that it will be with Pogba in their midfield two.
Sancho and Greenwood take a back seat
While Cristiano Ronaldo scored a brace and proved decisive on his Old Trafford return, United’s stars of the future in Mason Greenwood and Jadon Sancho had quiet games in their attack.
Greenwood may have provided the shot which led to Ronaldo’s opener, but the 19-year-old had his least effective game of the season so far out on United’s right wing.
Sancho, who was making his first start at Old Trafford, had a difficult game on United’s left and did not look entirely comfortable being deployed in that position. He is still incredibly new to the club and is still settling in, but the wait to see the Sancho of Borussia Dortmund goes on for now.
You could argue that given the arrival of Ronaldo, neither player was starting in their preferred position. Ronaldo took Greenwood’s position up front while the 19-year-old was in Sancho’s favoured slot on the right.
It remains a key priority for Ole Gunnar Solskjaer to develop both players, but on this showing it may be a task made harder by the arrival of 36-year-old Ronaldo.
Newcastle almost rip up the script
To the frustration of Steve Bruce, Newcastle were seconds away from achieving what they set out to do during their first-half performance at Old Trafford.
Even by their own standards, the visitors set out to be incredibly deep and frustrate their opponents, and it was working until Woodman spilled Greenwood’s shot and Ronaldo tapped into the rebound on the verge of half time.
The plan had been working, with Jamaal Lascelles and Ciaran Clark clearing every ball in the centre of defence and Javier Manquillo and Matt Ritchie winning their individual battles out wide. The brilliant Allan Saint-Maximin provided the threat on the counter attack while Joe Willock and Matty Longstaff had chances following runs from deep.
In fact, Newcastle’s approach went on to pay dividends when Miguel Almiron broke clear and Saint-Maximin set up Manquillo to score their equaliser on the counter-attack. Newcastle had been wasteful from such positions in the first half, but it showed that the goal had been coming.
Of course Newcastle fans would have wanted their team to show more ambition - but that approach was the sensible one to take. They were eventually undone as Ronaldo scored a brilliant second, before United ran up the score as the game opened up late on - but Newcastle's performance this season will not be defined by results such as this.
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