Arsenal defeated Manchester United 3-0 in the opening 20 minutes of an entertaining match at the Emirates Stadium as the Gunners moved up to second in the English Premier League table.
Sanchez added a third from 18 yards as the Gunners gunned united for just the second time in 14 league meetings.
Manchester United improved after the break but found it difficult to pass Arsenal defence line, the defeat leaves Louis Van Gaal’s side in third place, behind Arsenal on goal difference.
Tottenham Hotspurs continued their impressive recent run as two superb free-kicks from Christian Eriksen earned them a point at Swansea.
Earlier, Romelu Lukaku’s equaliser earned Everton a draw against Liverpool in the 225th Merseyside derby.