PREM: Arsenal 2-0 Hull City
Sanchez's goal was allowed to stand despite the ball clearly going in off his hand
Alexis Sanchez scored a controversial opener and a late penalty as Arsenal won for the first time in three, easing the pressure on Arsene Wenger with a 2-0 victory over Hull.
The Chile international unwittingly used his arm to turn Eldin Jakupovic's goal-line clearance into the back of the net on 34 minutes before he converted a penalty after Sam Clucas' handball prevented Lucas Perez's stoppage-time header.
Oumar Niasse and Lazar Markovic were a constant threat for Hull before they were reduced to 10 men but they failed to strengthen the club's survival bid for as Marco Silva tasted defeat in the Premier League for only the second time.
The victory momentarily moves Arsenal into third, level on points with Tottenham and nine behind Chelsea, while Hull remain 18th, a point from safety.
Wenger made one change after last week's demoralising defeat at Chelsea, as Kieran Gibbs replaced Nacho Monreal at left-back to make his first league appearance since Boxing Day. Silva, meanwhile, handed Niasse and Markovic starts as Abel Hernandez and Evandro dropped out after Hull's victory over Liverpool.
After their title hopes were all but extinguished at Stamford Bridge, there was a subdued atmosphere at the Emirates that had nothing to do with the freezing conditions and pre-match snow flurries. It was clear the on-looking Wenger, serving the last game of his four-game touchline ban, had rallied his troops ahead of kick-off, with the hosts making a lively start to warm those in attendance.
After Arsenal's bright start Hull almost stunned the Gunners with a 10th-minute counter, but after Markovic had nicked possession off Alex Iwobi, Niasse couldn't get a toe on the Serb's dangerous ball across the six-yard box. That encouraged the visitors, who went close on 14 minutes when Niasse towered above Laurent Koscielny to head Kamil Grosicki's cross on target, drawing Petr Cech into a fine save.
Arsenal responded but couldn't find the target as Hector Bellerin flashed wide before Sanchez dragged a left-footed effort inches wide. However, Hull's resolve was finally broken nine minutes before the interval when Gibbs' shot was cleared off the line by Robertson, popped up and cannoned of Sanchez's arm into the goal.
After consultation with his linesman, unsighted referee Mark Clattenburg allowed the goal to stand, much to the dismay of the Tigers. The setback failed to derail Silva's men, who started the second half in strong fashion, with Markovic and Niasse key on 51 minutes.
Markovic outwitted Koscielny, burst into the Arsenal half and crossed to find Niasse in the area where the on-loan Everton striker stung Cech's palms with a rasping drive. There was another officiating flashpoint four minutes later when last-man Gibbs saw yellow, and not red, for clearing Markovic out as he tried to latch onto Niasse's flick.
Space began to open up for both teams as the game wore on but Iwobi was unable to exploit it as he curled a shot over on the hour. From there on, Arsenal's attacking threat steadily diminished, allowing Hull to mount a late rally. Markovic rose high to get on the end of Harry Maguire's 77th-minute cross only to power a header wide, and there was more profligacy from Niasse as drilled the ball into the side-netting three minutes later.
Substitute Adama Diomande then headed over before their hopes evaporated when Clucas saw red for blocking Perez's goal-bound header and Sanchez crucially killed the game off from 12 yards to hand Wenger and his team-mates a timely morale-boost.