By Alan BaldwinLONDON,(Reuters)-Saturday’s Premier League goal glut turned into a trickle yesterday but Diego Costa’s class still shone through as he fired Chelsea to a ninth win in a row and back to the top of the table.The Spain international’s fine second-half strike at Stamford Bridge secured a 1-0 victory over a defensive West Bromwich Albion that restored the Blues’ three-point advantage over Arsenal.The Gunners had taken the overnight lead on goals scored after coming from behind to defeat Stoke City 3-1 at the Emirates.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.With the game heading for a goalless stalemate, Costa seized on a 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 all of last season.“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.”Chelsea’s scoreline in yesterday’s early match was 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.Henrikh Mkhitaryan opened his league account for Jose Mourinho’s United, days after scoring his first for the club in the Europa League, with a sizzling first half strike.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.United remained sixth with 24 points, three behind fifth-placed Tottenham who might otherwise have overtaken Manchester City on goal difference.Third-placed Liverpool, four points behind Arsenal, were playing struggling West Ham United at Anfield in the later kickoff.Southampton recovered from the disappointment of their midweek Europa League elimination to return to winning ways in the Premier League.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.