Juan Mata scored on his Chelsea debut to complete a 3-1 victory over Norwich on Saturday in a Premier League match overshadowed by teammate Didier Drogba being knocked unconscious.

Mata, who joined from Valencia this week, netted in the 11th minute of stoppage time, which resulted from Drogba requiring treatment on the pitch after being accidentally punched by Norwich goalkeeper John Ruddy.

While the Ivory Coast striker was taken to hospital, Chelsea said he only had ''mild concussion'' and would be released on Saturday night.

''He is showing some good signs of recovery for us to be a little bit more tranquil,'' Chelsea manager Andre Villas-Boas said.

Frank Lampard restored Chelsea's lead from the penalty spot after Grant Holt canceled out Jose Bosingwa's early opener.

Chelsea was kept off the top of the standings on goal difference by Liverpool, which beat Bolton 3-1 after goals from Jordan Henderson, Charlie Adam and Martin Skrtel.

Also Saturday, Franco Di Santo scored twice as Wigan beat Queens Park Rangers 2-0 and Mikel Arteta's penalty gave Everton a 1-0 win at Blackburn, which failed to score from two penalties against U.S. goalkeeper Tim Howard.

There were scoreless draws between Aston Villa and Wolverhampton Wanderers, and Swansea and Sunderland.

Among Sunday's fixtures, Manchester United takes on Arsenal and Manchester City is at Tottenham.

At Stamford Bridge, Chelsea got off to the perfect start when Bosingwa scored his first goal since November 2008.

Just six minutes had elapsed when the Portugal defender found the back of the net from 25 meters (yards) via the inside of the post.

Norwich, though, was back in the game in the 63rd after Chelsea goalkeeper Hilario needlessly came racing off his line to claim a cross and collided with Branislav Ivanovic, allowing Holt to hook the ball into the empty net.

It got worse for the hosts as they tried to regain the lead, with Drogba knocked unconscious after an aerial challenge with Ruddy.

Doctors raced onto the pitch to treat the 33-year-old striker, with the game stopped for seven minutes while he was loaded onto a stretcher and carried off wearing a breathing aid.

The game turned back in the Blues' favor when a breakaway by Chelsea brought a penalty scored by Lampard.