Colchester boosted their League Two play-off challenge with a deserved 2-0 victory at Crawley.Goals in each half from Mikael Mandron and Sammie Szmodics extended the U's unbeaten league run to four games.Crawley were forced into a late change when goalkeeper Glenn Morris hurt his back in the warm-up, and his replacement Yusuf Mersin was beaten after only four minutes.Following a strong run by Drey Wright, Cedric Evina failed to clear inside the his own area and Mandron stroked the ball home from 10 yards.Crawley had gone into the game unbeaten at home since October 17 and the hosts threatened for the first time when Evina put a shot narrowly wide.The Reds' top scorer Jordan Roberts was slow to react after Lewis Young found him with a deep cross before Mersin held a low shot from Ryan Jackson at the other end.Colchester leading marksman Szmodics doubled the advantage with his seventh goal in eight games and 12th of the season on 58 minutes.Szmodics seized on a through ball from Brandon Comley to expertly lob Mersin.Crawley were spared a heavier defeat when Szmodics put an angled drive against the crossbar in the 66th minute.