LONDON (Reuters) - Chelsea striker Diego Costa's class shone through as he fired them back to the top of the Premier League on Sunday with a 1-0 win over West Bromwich Albion as the previous day's goal glut turned into a trickle.
The Spain international's fine second-half strike at Stamford Bridge toppled a defensive West Bromwich Albion side and restored the Blues' three-point advantage over Arsenal as they chalked up their ninth league victory in a row.
The Gunners had taken provisional top spot with 34 pooints from 15 games on goals scored after recovering to beat Stoke City 3-1 at the Emirates on Saturday.
"It was a tough game," said Chelsea manager Antonio Conte. "We played with passion. West Brom is a tough team, a physical team who are difficult to break down. It was a good win and now we must continue.
"We have won nine in a row which is fantastic because this league is very tough. We are working very well."
All six home teams in action on Saturday scored at least three goals, with Jamie Vardy bagging a hat-trick as champions Leicester City returned to form with a 4-2 home win against Manchester City.
Sunday's opening three matches all ended 1-0, Chelsea's early scoreline reflected later at Old Trafford and St Mary's with Manchester United and Southampton seeing off Tottenham Hotspur and Middlesbrough respectively by the same margin.
Only the porous defences of third-placed Liverpool, now three points adrift of Arsenal, and struggling West Ham United raised the average with a 2-2 draw at Anfield in the later kickoff.
Liverpool manager Juergen Klopp, whose side lost 4-3 at Bournemouth last weekend, would still have been happier to see fewer goals on the scoresheet.
"The goals could have been avoided. That's how it is in football. Mixed emotions, it's still a point. A draw doesn't feel too good. doesn't feel too bad," he said.
With the game at Chelsea heading for a stalemate, Costa seized on a West Brom defensive error to break the deadlock with a superb shot into the top left corner in the 76th minute.
It was the league top scorer's 12th goal of the campaign, as many as he netted in the whole of last season.
Manchester United's Henrikh Mkhitaryan opened his league account with a sizzling strike just before the half-hour mark for Jose Mourinho's side, having scored his first for the club in the Europa League on Thursday.
The Armenian midfielder's afternoon ended painfully, however, when he was taken off on a stretcher with 10 minutes remaining after a heavy tackle left him clutching his ankle.
The Portuguese coach played down Mkhitaryan's injury, saying it looked more serious than it was and that he could be out for a week.
"Maximum a couple of weeks. It doesn't look like something that is very dangerous or difficult. He brings everything I want an attacker to play. Maybe one week out and it is better to be fresh for Boxing Day (Dec. 26)," he said.
United remained sixth with 24 points, three behind fifth-placed Tottenham who might otherwise have overtaken Manchester City, who are fourth, on goal difference.
Southampton recovered from the disappointment of their Europa League elimination to return to winning ways.
Their goal came in the 53rd minute when Sofiane Boufal picked the ball up from James Ward-Prowse and unleashed an unstoppable left-foot shot to claim his first league goal.
Editing by Tony Jimenez and Ken Ferris