text: The hosts had been on top when the ball came off forward Sanchez's hand and ended up in the net on 34 minutes. He added a penalty in injury-time which was awarded after Sam Clucas was sent off for handball from Lucas Perez's header.
  In between, Hector Bellerin and Sanchez both failed to hit the target and Mesut Ozil volleyed over the crossbar for Arsenal.
  Striker Oumar Niasse had Hull's best chances - his header and low strike forced Petr Cech into sharp saves - while Adama Diomande nodded over late on.
  Arsenal had been pressing for the opener before Sanchez's intervention.
  The visitors failed to clear Kieran Gibbs' low shot and as the ball ricocheted off goalkeeper Eldin Jakupovic on the ground it bounced off the Chilean's hand and into the net.
  For a deliberate handball, Football Association laws state:
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  On this occasion, Sanchez did not look like he purposefully pushed the ball into the net and he had little time to move out of the way after the ball came off Jakupovic.
  After consultation with his assistant, referee Mark Clattenburg awarded the goal, but prior to that in the first half, Theo Walcott had a shot blocked by the hand of Clucas inside the area, for which no penalty was given.
  After the game, Hull defender Andrew Robertson told Sky Sports that Clattenburg had apologised to the Hull players after half-time.
  Robertson added: "The ref told us he didn't give it because he wasn't 100% sure. Not many referees can admit they're wrong, so it's good when he does, though it doesn't make things better."
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  Chasing the game in the second half, Hull's Lazar Markovic was running onto a long punt forward deep in the Arsenal half.
  The Serb was barged down by Gibbs, who was the last defender, and had the on-loan Liverpool man not been infringed, he would have had a clear run through on goal from 30 yards.
  Clattenburg spotted the incident and presented a yellow card.
  Gibbs said after the game: "I took a chance with the challenge on Markovic. The ref said the ball was going away from goal."
  When asked if Gibbs should have been sent off, Hull boss Marco Silva said: "Yes. It is true. Markovic go to the goal."
  With Hull pushing for an equaliser, they were hit on the counter by the home side. Jakupovic came sprinting off his line as Sanchez went round him and picked out Perez at the back post, but the Spaniard's goal-bound header was kept out by Clucas' arm on the line. Clucas was given a red card for the incident.
  Sanchez stepped up to take the penalty, drilling a low finish into the net, which was his seventh goal against Hull in just four games.
  It was also his 17th top-flight strike this season, making him the league's leading marksman.
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  Arsenal had lost back-to-back league games against Watford and Chelsea to leave their title challenge in disarray.
  But the win moves them up to third in the table, nine points behind leaders Chelsea.
  For Hull, it was an unlucky defeat, having come close to scoring in both halves, but they have now failed to find the net in 12 of their 25 games - more than any other side.
  Despite the defeat, Tigers supporters will be buoyed by the impact made by new manager Silva as his side look well-equipped for a battle to stay in the top-flight, yet they remain in the relegation zone by a single point.
  Former Hull defender Peter Swan on BBC Radio Humberside
  Hull City's performance was strong, and they did really all they could. The referee's decisions have hurt Hull today, but the side are showing they have got a very real chance of staying up.
  For the second goal, you have got to feel sorry for Clucas. His keeper has stitched him right up. It was an easy decision for Clattenburg.
  And do you want to know the irony? Jakupovic had probably made up the ground and was covering behind Clucas, not that the defender knew.
  Arsene Wenger speaking to Match of the Day: "We were resilient, focused and organised, but a bit with the handbrake on as we were under pressure to win the game. In the end perhaps we were fortunate to get away with a positive result.
  Hull boss Marco Silva told BBC Sport: "The most important thing is the result. It was a very good second half. We had control of it and caused Arsenal problems.
  "They started the game better than us and after the story of the first half they score with handball. We didn't deserve this result.
  Arsenal travel to Bayern Munich for the Champions League last-16 first leg fixture on Wednesday (kick-off 19:45 GMT), while Hull host Burnley in the Premier League next Saturday (15:00).
  Match ends, Arsenal 2, Hull City 0.
  Second Half ends, Arsenal 2, Hull City 0.
  Attempt missed. Danny Welbeck (Arsenal) right footed shot from the centre of the box is high and wide to the right. Assisted by Héctor Bellerín.
  Goal!  Arsenal 2, Hull City 0. Alexis Sánchez (Arsenal) converts the penalty with a right footed shot to the centre of the goal.
  Delay over. They are ready to continue.
  Delay in match Andrew Robertson (Hull City) because of an injury.
  Sam Clucas (Hull City) is shown the red card.
  Penalty conceded by Sam Clucas (Hull City) with a hand ball in the penalty area.
  Attempt blocked. Lucas Pérez (Arsenal) header from the centre of the box is blocked. Assisted by Alexis Sánchez.
  Attempt missed. Ahmed Elmohamady (Hull City) right footed shot from outside the box misses to the left following a corner.
  Corner,  Hull City. Conceded by Héctor Bellerín.
  Harry Maguire (Hull City) wins a free kick in the attacking half.
  Foul by Alexis Sánchez (Arsenal).
  Offside, Arsenal. Kieran Gibbs tries a through ball, but Mesut Özil is caught offside.
  Hand ball by Ahmed Elmohamady (Hull City).
  Attempt missed. Adama Diomande (Hull City) header from the centre of the box is too high. Assisted by Evandro with a cross following a corner.
  Corner,  Hull City. Conceded by Danny Welbeck.
  Attempt saved. Andrea Ranocchia (Hull City) header from the centre of the box is saved in the centre of the goal. Assisted by Evandro with a cross.
  Hand ball by Francis Coquelin (Arsenal).
  Foul by Kieran Gibbs (Arsenal).
  Lazar Markovic (Hull City) wins a free kick on the right wing.
  Substitution, Arsenal. Lucas Pérez replaces Alex Oxlade-Chamberlain.
  Substitution, Arsenal. Danny Welbeck replaces Alex Iwobi.
  Foul by Mesut Özil (Arsenal).
  Andrea Ranocchia (Hull City) wins a free kick in the defensive half.
  Attempt missed. Oumar Niasse (Hull City) header from the right side of the six yard box is close, but misses to the right. Assisted by Evandro with a cross following a corner.
  Corner,  Hull City. Conceded by Alex Iwobi.
  Substitution, Hull City. Adama Diomande replaces Tom Huddlestone.
  Attempt saved. Lazar Markovic (Hull City) header from the centre of the box is saved in the bottom left corner. Assisted by Harry Maguire with a cross.
  Offside, Arsenal. Alex Oxlade-Chamberlain tries a through ball, but Mesut Özil is caught offside.
  Alexis Sánchez (Arsenal) is shown the yellow card.
  Alexis Sánchez (Arsenal) has gone down, but that's a dive.
  Attempt missed. Harry Maguire (Hull City) header from the centre of the box is high and wide to the left. Assisted by Evandro following a set piece situation.
  Foul by Alex Iwobi (Arsenal).
  Lazar Markovic (Hull City) wins a free kick on the right wing.
  Attempt missed. Shkodran Mustafi (Arsenal) header from the centre of the box is high and wide to the left. Assisted by Mesut Özil with a cross following a corner.
  Corner,  Arsenal. Conceded by Ahmed Elmohamady.
  Alexis Sánchez (Arsenal) wins a free kick in the defensive half.
  Foul by Ahmed Elmohamady (Hull City).
  Andrea Ranocchia (Hull City) is shown the yellow card for a bad foul.
target: Alexis Sanchez scored twice as title-chasing Arsenal beat relegation-threatened Hull in controversial circumstances in the Premier League.