Gabriel Martinelli scored his first hat-trick with Arsenal as the Premier League leaders beat struggling Portsmouth in the second division 4-1, reaching the fourth round of the FA Cup on Sunday.Arsenal, which holds the record for the number of times it has won the FA Cup (14 times), trailed by a goal in the third minute when Colby Bishop raised the level of enthusiasm at Fratton Park by scoring a goal from a rebound after goalkeeper Kepa Arrizabalaga made a save.But this delay lasted only five minutes, as Arsenal equalized the score with their first goal out of three goals from corner kicks.Portsmouth was unable to handle a free kick and the ball eventually entered the goal after colliding with Andre Dozel from the home team.Martinelli put the visitors ahead when he converted Noni Madueke's corner into the net in the 25th minute, then hit the post shortly afterwards from close range.Madwicki missed a penalty just before half-time to keep Portsmouth in contention,...He completed his personal hat-trick with a header as Portsmouth were once again unable to defend from a free kick taken by Arsenal.Arsenal have now scored 17 corner goals this season.Earlier on Sunday, Leeds United, competing in the Premier League, came back from a goal down to win 3-1 over second-tier Derby County