Wanted: easy warm-up match for debutant goalkeeper only a fortnight back from eight months out injured. Applicants must show willingness to roll over and offer no threat on goal. Recent victims of a thrashing considered a bonus. Derby County? They will do nicely. Yet, while the scoreline indicates that Cristiano Ronaldo was Manchester United’s match-winner, Ben Foster, the young England goalkeeper who had been obliged to wait three years for this day, deserved a share of the plaudits as his team regained leadership of the Barclays Premier League.

Sure, Ronaldo scored with the ninth of his 11 chances as United threatened to tear Derby apart in the manner that Chelsea had three days earlier in winning 6-1 at Stamford Bridge, but when the bottom team, galvanised by surviving an onslaught for the first 38 minutes in a cup-tie atmosphere, realised that they were in with half a chance, Foster came into his own. But for his two brilliant saves from Kenny Miller’s shots within 60 seconds near the end of the first half, Derby could have been eyeing a shock victory.

Give Derby hope and they can look as if they belong among the elite. At home against Chelsea (a 2-0 defeat, with a “goal” by Miller wrongly given offside at 1-0 down), Liverpool (a 2-1 defeat, with Steven Gerrard scoring the winner in the last minute) and United, they have produced their best. It is against fellow strugglers that Derby look like a side doomed to relegation and Middlesbrough, who play them at the Riverside Stadium next Saturday, must be licking their lips.

After Foster’s party pieces, United settled into workmanlike mode, accepted that this was not a day for showboating, and ground out the victory. Wayne Rooney tore down the left and crossed for the unmarked Ronaldo to sidefoot past Roy Carroll his 31st goal of a remarkable season.

Foster, 24, is ready to go on loan to a Coca-Cola Championship club as he continues his rehabilitation from a ruptured knee ligament. Edwin van der Saar is out only temporarily with a groin injury, while Tomas Kuszczak, United’s second-choice goalkeeper, will be available for the match at home to Bolton Wanderers on Wednesday after suspension.

“I’m not expecting to be in goal in front of any other goalkeepers so soon,” Foster said. “I’ve only been back from injury two weeks, really, and I was delighted to get the game. I thoroughly enjoyed it and I’m delighted to get the win and keep a clean sheet. I’m quite happy with my performance, too.

“The two chances came pretty quick-fire and I just remember making two reaction saves. I thought it might be an ideal game to make my debut in, especially with them coming off the back of a 6-1 defeat. I thought they’d be down a bit and it might be a quiet game for me, but I was a bit busier than I thought I’d be.”

Having proved himself playing at the bottom of this league last season, during his two-season loan spell with Watford that led to an England debut last year, Foster earned praise from Ryan Giggs for displaying a different set of attributes. “Credit to him, in his first game back,” the United captain said. “We all know what he’s capable of. Last season he was used to making saves all the way through the game, but at United it’s a bit different. You have to keep your concentration and he did that for the first half-hour and, like Edwin’s done, when they’re called upon, they do their stuff. Today he’s proved he can do that.”

David Jones, who excelled in the Derby midfield against his former teammates, said: “I’m pleased for him. He suffered a horrific injury and he’s been out for over a year, so it was good to see him back. Maybe I would have preferred to see him back one week later. He played brilliantly.” Jones and Robbie Savage – finally firing on all cylinders, to earn the chants of the stoic home supporters – saw off Paul Scholes and Anderson, both of whom were substituted. Savage even outsprinted his teammate to swap shirts with Ronaldo after the final whistle. “This last seven games I’ve been rubbish,” Savage, who also started his career at Old Trafford, said. “But for my own personal self-esteem, to play like that, I’m delighted, and Dave Jones looks a player.”

How they rated

Derby County (4-4-2): R Carroll 7 M Edworthy 5 D Leacock 6 D Moore Y 6 J McEveley Y 4 M Sterjovski 6 R Savage Y 6 D Jones Y 7 E Lewis 6 K Miller 6 R Earnshaw 5
Substitutes: A Todd (for Edworthy, 55min), E Villa (for Earnshaw, 77), L Robert (for Sterjovski, 83).
Not used: L Price, H Ghaly.
Next: Middlesbrough (a).

Manchester United (4-4-2): B Foster 7 J O’Shea 6 W Brown 6 N Vidic 7 P Evra 6 Park Ji Sung 5 P Scholes 5 Anderson 5 R Giggs 6 C Ronaldo 8 W Rooney 7
Substitutes: L Saha 6 (for Park, 62min), M Carrick 5 Y (for Scholes, 62), D Fletcher (for Anderson, 74).
Not used: T Heaton, O Hargreaves.
Next: Bolton (h).

Referee P Dowd

Attendance 33,072