Afonso Alves slowed Manchester United's title charge with an excellent double to earn Middlesbrough a draw at the Riverside. The result sees United take a three-point lead over Chelsea - and they still have to go to Stamford Bridge.

Gareth Southgate's side were worth the point and could even have stolen a late winner. United could point to several chances apart from Cristiano Ronaldo's 37th goal of the campaign and an equaliser from Wayne Rooney, but there was an unusual frailty in defence. John O'Shea was never comfortable and Rio Ferdinand also limped off in the second half.

The biggest crowd of the season at the Riverside witnessed a hugely-entertaining encounter, Alves warming things up with a promising early run into the United penalty box. The home fans were left cold however when their side's marking completely went to pieces and United scored a 10th-minute opener.

First Michael Carrick found himself in the clear at the rear of the area to pick up possession from corner, and then Ronaldo drifted away from his marker to fire home his cross from inside the six-yard box.

Alves showed a couple of flashes, including a decent downward header, as Boro tried to reply then Ryan Giggs hit the side-netting after some stylish interplay between Ronaldo and Rooney.

Jeremie Aliadiere was then guilty of a horrendous miss after Middlesbrough broke at speed, the French striker pulling the ball wide from a one-on-one position.

Afterwards, United players complained bitterly that referee Mike Riley did not halt play to allow Patrice Evra to receive treatment - Edwin van der Sar even had to push Ronaldo away from the match official. Riley, though, was following the FA's rules to the letter and Evra was soon back on his feet anyway.

Ronaldo then showed human blood does flow through his veins after all. A thrilling run saw the Portuguese winger leave Gary O'Neil trailing in his wake but when he cut into the penalty box his finish for once lacked composure and was sliced wide.

Alves won a free-kick against Ferdinand 30 yards out and took it himself. It was a terrific effort too, curling and dipping wickedly but straight at van der Sar, who was up quickly again to claw away the follow-up header from Emmanuel Pogatetz.

But the Brazilian was not to be denied again and 10 minutes before the break he scored an excellent equaliser.

O'Neil's long pass from the right caught United ball-watching, Aliadiere's flick-header took it into Alves's path and he kept his cool to lift the ball over the sliding van der Sar with his left foot.

Boro came agonisingly close to taking the lead when George Boateng found Stewart Downing on his own at the far-post but United's Dutch international goalkeeper was out like lightning to block the shot.

Ronaldo was then furious again when a powerful strike appeared to be blocked by Andrew Taylor's arm - Riley only awarded a corner.

Alves's equaliser had been the first goal conceded by United since February 23 so when he put Boro ahead in the 56th minute, the majority of the 33,952 crowd went mad with a combination of excitement and disbelief.

Again Aliadiere played a part, the ball coming off his head into Alves's stride and the Brazilian this time finished expertly with his right foot.

United were well and truly rocked and Alves nearly sealed the perfect hat-trick but his goalbound header struck Ferdinand's knee.

Rooney, who had been out of sorts all match, was booked for following through on Mark Schwarzer. Sir Alex Ferguson had seen enough and took off O'Shea, pushed Wes Brown to centre back and sent on Owen Hargreaves.

Downing then embarked on a penetrating run that saw him outpace two defenders but his drive from a tight angle only found the side-netting.

Rooney, who had looked close to boiling point, finally found an outlet to his frustration when substitute Park Ji-Sung beat Taylor and centred for the England striker to clip home from close range off Pogatetz's leg.

With 10 minutes to go, Alves departed to a standing ovation as Southgate sent on Tuncay to hunt for a winner.

As the clock ran down the tension increased and both sides had chances to seal it in a frantic finish.

First, van der Sar pulled off a diving save to deny Aliadiere then Rooney dragged his effort wide from a threatening position.

Tuncay looked poised to steal it in injury-time after a brilliant turn - but van der Sar once again proved United's saviour.