Ole Gunnar Solskjaer struck in injury time to earn Manchester United a 2-1 victory over Aston Villa at Old Trafford in the third round of the FA Cup.
The game had been heading for a draw after Henrik Larsson scored on his United debut only for Milan Baros to equalise.
After United had dominated the first half without really threatening a goal. Larsson, who has joined on a short-term loan from Helsingborgs, broke the deadlock in the 55th minute.
The former Swedish international striker was picked out by Wayne Rooney and finished cleanly from 15 metres.
From then on it became a stream of United attacks with Ryan Giggs, Rooney and Ronaldo all going close.
However, the 11-times Cup winners then paid for their failure to finish as Villa finally roused themselves into a brief period of pressure.
After Gary Cahill and Isaiah Osbourne had threatened, substitute Baros beat stand-in goalkeeper Tomasz Kuszczak with a low shot after seizing on weakly-struck Cahill effort.
Just as it seemed Villa would hold out for the draw, Rooney fed Solskjaer in the inside right channel and the Norwegian striker, on as a 78th minute replacement for Larsson, fired in a crisp first-time shot that on-loan Hungarian international goalkeeper Gabor Kiraly somehow allowed through his grasp and over the line.
Villa boss Martin O'Neill paid tribute to his former striker Larsson.
O'Neill, who managed Larsson during his glory years at Celtic, was in a state of disbelief.
But he was generous in his praise of Larsson, now 35.
He said: 'He is always capable of scoring a goal like that. People said he would only score goals in Scotland and I never thought for one minute he wouldn't score in any league he chose. He has gone on to show that.'
United manager Sir Alex Ferguson expects Larsson to build on this display.
Ferguson told MUTV: 'He could have scored two or three goals. With his movement and experience, he was terrific. The goal summed him up, no draw back.
'Henrik has scored goals throughout his career and some of them have been crucial. Eric Cantona was like that here.'
