Ronaldo rocket maintains Manchester United's unbeaten Champions League record

With Wayne Rooney still sidelined with ankle trouble, Saha has been handed two opportunities to convince Sir Alex Ferguson he is worth retaining. He struggled at Bolton at the weekend and struggled again in this match.

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It took Tevez's closerange equaliser in the 61st minute and a sensational injury-time free-kick from Ronaldo to help United overcome a first-half deficit and head for the second phase of the competition as group winners.

With United offering up some rather uncertain play in the opening period, Lisbon were allowed to take the lead when goalkeeper Tomasz Kuszczak misread a shot from defender Fernando Abel that fizzed past him at the near post in the 22nd minute.

United improved tangibly in the second period as Tevez and Ryan Giggs were sent on as substitutes. Ronaldo, in particular, was a spellbinding influence.

It was, however, another night of anonymity from Saha that will give Ferguson plenty to think about ahead of the transfer window.

The United boss has previously indicated he will adhere to his preferred policy of not interfering with his squad when the rest of Europe begins its annual winter bargain hunt.

He must, however, be beginning to wonder if that is now the way forward.

With the likes of Bolton's Nicolas Anelka still on his radar, Ferguson is aware he would be given money to spend if he feels his squad needs fresh impetus.

Saha is simply providing evidence that a phone call to the Glazer family may be in order. He is a talented footballer; quick, intelligent and with the ability to finish calmly. But at Bolton and against Sporting he was poor.

Seemingly drained by the toll of persistent injuries and the knowledge that some have doubts about his ability to cope with the rigours of a full season, the Frenchman cuts a sorry figure.

Ferguson has been supportive in public but the fact that Saha was hauled off and replaced by a midfielder — Owen Hargreaves — as United chased victory says everything.

Saha looked shot to pieces as he trudged off the field and no wonder. Once again, Ferguson offered only encouragement and suggested his player merely needs games.

The United manager said: "His last full game before Saturday was last December and we should think about that before talking about touch and confidence. That is the important issue with Louis.

"We are trying to manage him and we are sure that his form will come."

While Saha must search for the ingredients that once made him such a powerful player, Ronaldo will now believe his own spell of relatively indifferent form is behind him.

Recalled to the team, the Portugal international was terrific. After creating his team's only chance of note in the first half — dragged across goal by Saha — his influence proved decisive.

The ball that he sent towards goal in the 61st minute was speculative and TV replays were unable to reveal for sure whether Tevez touched it in from six yards or whether the final contact came from Sporting defender Marian Had. It didn't matter.

United were back in the game and the momentum they subsequently developed earned a fifth successive win in the competition.

Hargreaves missed one chance soon after coming on as goalkeeper Rui Patricio saved with his left leg, while Nemanja Vidic sent a free header over from a corner.

A draw seemed likely but Ronaldo, as usual, had a different vision of how the night might end. Sporting's tackling became rash as the game wore on and another lunge gave Ronaldo his chance from 30 yards in time added on.

The keeper should have saved the free-kick that flew hard but true. But a step to the right prior to Ronaldo's shot left him with too much to do as the ball arrowed in to his left-hand corner.

Ronaldo, of course, had broken Sporting's hearts with the winner at his old club in September. That time there has been no celebration, only a graceful apology.

This time it was different as he said: "The people of Sporting know that this is my club now. I was just happy to score. I practise those freekicks. It was important that we won the group."

MAN UNITED (4-3-2-1): Kuszczak 5; O'Shea 6, Ferdinand 6, Vidic 6, Evra 7; Fletcher 6 (Tevez 46, 7), Carrick 6, Anderson 5; Ronaldo 8, Nani 5 (Giggs 46, 7); Saha 5 (Hargreaves 77). Booked: Ronaldo, Evra.

SPORTING (4-3-1-2): Rui Patricio 6; Abel 6, Tonel 6, Polga 7, Had 6; Moutinho 6, Veloso 6, Izmailov 7 (Gladstone 80); Romagnoli 6 (Vukvecic 66, 6); Purovic 6, Liedson 6. Booked: Had, Polga.

Man of the match: Cristiano Ronaldo.

Referee: Claus Bo Larsen (Den).