United do it the hard way after Hernandez gives them fine start

Manchester United 2 Marseilles 1 (Man Utd win 2-1 on aggregate)

It is another season of living dangerously at Manchester United, yet for a team who again insisted upon tiptoeing along the brink of calamity last night they find themselves in the Champions League quarter-finals draw on Friday with the possibility of a second historic treble still on the cards.

Beset with injuries, especially to a defence that wobbled alarmingly at times, United won this game because they had its shrewdest penalty-area assassin in Javier Hernandez. The divine being to whom the Mexican appeals on his knees before kick-off was not just smiling on his young devotee last night, he appeared also to be wearing a red and white scarf.

United needed their good fortune at times. They lost two right-backs to injury – John O'Shea and then Rafael da Silva, who had been sent on to replace him – and having rode their luck, they conceded an own goal through Wes Brown with eight minutes left. Had Marseilles possessed a striker with just half Hernandez's composure, then Sir Alex Ferguson might have been left to concentrate on the Premier League and the FA Cup.

His team were without Nemanja Vidic again who was ruled out with a calf injury and with Rio Ferdinand already missing, the responsibility was on Brown and Chris Smalling once again. They muddled through in the end but there were a few anxious moments.

On the encouraging side, there was a performance from Wayne Rooney, particularly in the first half, that was reminiscent of his long-lost form from before last March. Playing just behind Hernandez, it was his passing that made United's first goal. That United are in the last eight, along with Tottenham Hotspur, is enough for now but how they approach Saturday's game at home to Bolton is quite another matter.

With no prospect of Ferdinand returning yet and Vidic, Rafael and O'Shea all doubtful, this is a United side that again requires patching up. Their options in attack and midfield are greater and should become even more plentiful with the imminent return of Park Ji-sung and Luis Anderson. Jonny Evans is back in training but the visit of seventh-placed Bolton is a test.

While United's back door swung open on its hinges at times last night they compensated with one of the best moves of the season for Hernandez's first goal within six minutes – thanks to the hard work and ingenuity of Rooney.

He started the move with a brilliant half-volleyed pass with the outside of his right foot to Ryan Giggs out on the left. Then Rooney put his head down and sprinted into the box to get it back. Collecting the return in the area, he beat everyone with his pass, including the Marseilles goalkeeper Steve Mandanda, so that Hernandez could sidefoot the ball in from less than a yard.

United's start suggested they were ready to tear Marseilles apart but it faded fast. As Ferguson had noted beforehand, this Marseilles team are blessed with an athletic, strong defence which relies heavily on the strength of left-back Taye Taiwo and the centre-half Souleymane Diawara, both of whom were impressive.

Taiwo was strong enough and fast enough to make Nani think twice about pushing the ball past him and chasing it down the right wing. Diawara, eventually caught out by Hernandez for his second goal, had the second of Marseilles' three good first-half chances. From Taiwo's cross on 36 minutes, he had a free header in the United area which he put wide.

But the best chance for the French side came just four minutes after Hernandez's opener. A well-judged flick from the winger André Ayew gave André-Pierre Gignac, the France international, a free run at goal. A £15m signing last summer, Gignac has struggled at Marseilles this season and it was not hard to see why in this instance. He snatched at his chance and put the ball well over.

Ten minutes before half-time, United lost O'Shea to a hamstring injury after he made a good run down the right. On came the volatile Rafael da Silva, who flew into an unwinnable challenge on Ayew shortly afterwards. Rafael was fortunate the Marseilles man chose to leap over him because it spared him a booking at a time in his career when he is picking up too many of them.

United had a shout for a penalty when Hernandez tumbled over Diawara in the 41st minute after Giggs cut the ball back to him but it looked like a collision engineered by the forward. A minute later and Marseilles had their third chance of the half when Loïc Rémy volleyed over when Smalling could not get enough distance on his clearance.

By the end of the first half, United had lost all the momentum created by that early goal. Rooney's best moment of the second half came at the start but he could not make that crucial second goal and gradually Marseilles came back into it. Only when the second of the Da Silva brothers came on – this time it was Fabio for his injured brother – did Ferguson use the break in play to change his team's system.

Ferguson brought Rooney out to the left of a three-man line behind Hernandez. Giggs was moved into the centre and Antonio Valencia, who had come on for Nani, played on the right. To give Ferguson his due, his tactical changes worked immediately.

On 75 minutes, Valencia turned on the ball down the right and returned the ball to Giggs with a sweetly timed pass inside the Marseilles left-back. Coming in from that wing he crossed the ball low for Hernandez who turned away from Diawara before the defender could react and tucked in his 16th goal of the season.

Before then, the game had started to look a little anxious for United. Rémy's ball across goal had been struck first time by Benoît Cheyrou into the arms of Edwin van der Sar. Earlier, Gabriel Heinze had misjudged a header from a corner.

Under pressure at another corner, Brown deflected the ball past Van der Sar to set up an anxious finish. Marseilles did not quite have the courage to finish United off, although they were given more than one invitation to do so.

Man of the match: Rooney.

Match rating: 6/10.

Referee: C Carballo (Spain).

Attendance: 73,996.