Manchester United are not yet at full pelt in their private race to overtake the neighbours at the top of the Premier League – the cavalry charges of old have become a rare sight this season – though if the task now is to hang on to Manchester City's coat-tails, to use Sir Alex Ferguson's expression, it was accomplished here with a minimum of fuss. Even the United manager must have been surprised at how effortlessly a three-point gap on the leaders was closed.

Two penalties earned United the points against a disappointing Stoke, who can frighten the best on their own ground but offered little threat of any kind in Manchester. It was a poor game and an unmemorable occasion, until news from Goodison filtered through midway through the second half and Old Trafford found its voice. The points are more or less all that matter now and as long as United keep going virtually any stage of the season could become a turning point and even a game as undistinguished as this could turn out to be important. Whoever imagined that Darron Gibson – whose name was being chanted towards the end – could prove potentially pivotal to United's campaign?

"We were very patient and kept our composure," Ferguson said. "This could be a significant win – we hope so – but it was the last day of January. March and April is still the important time and we have [a trip to] Manchester City at the end of April."

With David de Gea ill and Anders Lindegaard injured in training Ferguson opted to hand Ben Amos a Premier League debut, with Tomasz Kuszczak on the bench. Jon Walters and Kenwyne Jones tried to test the new goalkeeper with long shots early in the game, though both flew harmlessly wide and Amos dealt with his first cross from Jermaine Pennant comfortably enough.

Ferguson has taken issue with Alan Hansen's complaints about United's recent performances, pointing out how many key players are out injured. That excuse will not wash for long, with Wayne Rooney, Nani and Ashley Young likely to return to the squad for Sunday's visit to Chelsea. Perhaps United will then be less reliant on Paul Scholes, who was surprisingly influential here considering his age and the fact it is less than a month since he returned. Scholes has become United's go-to man again, not only setting the tempo in midfield but frequently looking the most likely to score a goal. The veteran almost had one with the best effort of the first half, a typical drive from the edge of the Stoke penalty area that shaved Thomas Sorensen's left-hand upright, though that possibly said more about the quality of the attacking play in the first half than the dynamism of Scholes's attempt.

Antonio Valencia did make a few inroads down the right, but United struggled to bring Javier Hernández or Dimitar Berbatov into the game, and it was another midfielder, Michael Carrick, who was next to shoot narrowly wide just after the half-hour. Stoke's first-half attacks were limited, mainly by United's cunning plan of cutting down their opponents' set-piece opportunities by keeping free-kicks to an absolute minimum.

Stoke must have wished they had thought of that when a softish penalty eight minutes before half-time saw United take the lead. Scholes played a short pass to set Park Ji-sung running towards goal, Pennant was hurried into a challenge that took the man as well as the ball and Hernández scored confidently from the spot. United appealed for another penalty shortly after, though as Ryan Shawcross had his back to Hernández's cross and the arm that hit by the ball was by his side it was always an optimistic shout.

As if to underline the paucity of chances created from open play the second half opened with a penalty appeal as well, this one given. It was just as soft, Walters tugging at Valencia's arm then trying to pretend he had not, but once the winger went to ground the referee had little option, as contact had been made. This time Berbatov took the kick from the spot, just managing to squeeze a low shot past Sorensen even though the goalkeeper went the right way.

Stoke tried to make a fight of it for a while, the substitute Cameron Jerome bringing a scrambling save from Amos with a header, though the goalkeeper did not have much else to do for the rest of the evening and probably ended up wondering if Premier League games were always going to be this straightforward. United were so relaxed they brought on Paul Pogba for the last 15 minutes and the substitute came as close as anyone else to scoring from open play – at least until Berbatov missed a stoppage-time sitter – only to see his shot blocked by Walters.

"We killed ourselves giving away two penaties," Tony Pulis said. "To have a chance here you have to keep it level for as long as possible. It's a very open title race now – anyone can drop points."