Diego Costa snaffled a stoppage-time equalizer to preserve interim manager Guus Hiddink's unbeaten record as Chelsea snatched a 1-1 draw at home to Manchester United Sunday. United looked to be closing to within four points of the Premier League's top four after Jesse Lingard's 61st-minute goal set Louis van Gaal's men on course for a third consecutive win in all competitions. But in the first of six minutes of injury time, added on for a serious-looking knee injury to Chelsea center-back Kurt Zouma, Costa rounded David de Gea to score, extending Hiddink's unbeaten run since succeeding the sacked Jose Mourinho to 10 matches. Chelsea remains 13th, 17 points below the top four, but while its Champions League qualification hopes have long seemed over, Costa's goal dealt a weighty blow to embattled United manager Van Gaal. Van Gaal bullishly dismissed speculation linking Mourinho with his job prior to the game, but finishes the weekend with his side six points below the top four. Buoyed by breezy recent wins over Derby County, in the FA Cup, and Stoke City, in the league, United had made a strong start, with Anthony Martial testing Thibaut Courtois in the 18th minute. Chelsea rallied, John Terry seeing a penalty appeal waved away after his shot hit Daley Blind on the arm, but after Zouma had been carried off following an awkward fall, United made the breakthrough. Cameron Borthwick-Jackson's cross was helped on by Wayne Rooney and Lingard took a touch before slamming in his second goal in two games. But after United goalkeeper De Gea had saved from Branislav Ivanovic and Cesc Fabregas, Costa equalized in stoppage time when he gathered Fabregas's pass, rounded De Gea and slotted home. Earlier, Mesut Ozil and Alex Oxlade-Chamberlain scored twice in a minute as Arsenal got its title challenge back on track by winning 2-0 at Bournemouth. Arsenal had slipped to fourth in the table after going four games without a win, but victory at Dean Court took them up to third, level on points with second-place Tottenham Hotspur and five points below leader Leicester City, which visits the Emirates Stadium next Sunday. Ozil opened the scoring in the 23rd minute, skilfully slamming home right-footed after Olivier Giroud nodded down Aaron Ramsey's flighted pass to claim his first goal since the 2-0 win over Bournemouth on December 28. Ramsey was also the architect of Arsenal's second goal a minute later, slipping a pass wide to the overlapping Oxlade-Chamberlain, who drilled a low shot in off the left-hand post for his first away goal in five years.