Wayne Rooney fired United in front midway through the first-half but Middlesbrough replied with two goals from Lee Cattermole and skipper George Boateng either side of the interval.

Portuguese winger Ronaldo converted home a penalty six minutes past the hour mark as United, top of the Premiership and into the last eight of the UEFA Champions League, claimed a draw at Riverside.

Both sides will meet again in a replay at Old Trafford on the 19th of March.

United's Dutch keeper Edwin van der Sar injured his calf in the warm-up and had to be replaced by Polish keeper Tomasz Kuszczak.

Argentinean Julio Arca could have given Middlesbrough an early lead in the seventh minute as he went through after dribbling past Gary Neville but his effort was brilliantly saved by Kuszczak.

The Red Devils were ahead in the 23rd minute through Rooney, whose low drive went directly to the far right bottom of Mark Schwarzer's net after being set-up by Ryan Giggs.

Giggs could have doubled the lead 10 minutes before the break when he met Neville's pinpoint cross with a left-footed volley that was denied by the left post.

Middlesbrough equalized one minute before halftime when Kuszczak missed Stewart Downing cross to find Arca setting up Cattermole who volleyed the ball brilliantly into the net.

Unmarked Dutch midfielder Boateng put Boro ahead one minute into the second-period when headed home Downing's corner at the far post.

Rooney claimed for a penalty in the 52nd minute for having his shirt pulled inside the area but the referee waved play on.

The visitors were compensated when Henrik Larsson's cross was handled by Boateng inside the area.

Ronaldo stepped-up before slotting home past Schwarzer.