AFP, MANCHESTER: David de Gea has challenged Manchester United to get as close as possible to runaway leaders Chelsea as Jose Mourinho's side battle to finish in the top four. It is one of the Premier League's stranger statistics that United have not moved from sixth position for three months, despite being unbeaten for 15 matches in the competition. Yet having beaten Leicester 3-0 last Sunday, Mourinho's men could finally climb a place or two should they beat Watford on Saturday, as long as Liverpool and Arsenal slip up. United looked to be back to something near their best at the King Power Stadium, after seeing their progress stalled by a run of three successive league draws. With a glut of cup matches coming up, this weekend's game will be their last league fixture for three weeks, so a win is needed to ensure that the top four do not get the chance to pull too far away. Spain international De Gea knows United are unlikely to win the title, but having the goal of reeling in Chelsea could bring the added benefit of boosting their bid to qualify for the Champions League. “I think we're in good form. We're on a 15-match unbeaten run in the league,” De Gea said. “The team are doing well. We must continue down this route to get into the top four as soon as possible. “Chelsea? The truth is that they're doing really well. I think they're nine points ahead of second place and they have the title in their hands. “We are all going to fight to get as close as possible but they are very well placed.” Mourinho is expected to use his usual 4-2-3-1 formation, despite causing a surprise by starting with a 4-4-2 set-up at Leicester. United began that game with Marcus Rashford in attack alongside Zlatan Ibrahimovic, but became far more effective when Mourinho reverted to his favoured formation, with the former Sweden striker playing as the lone forward. Rashford moved out to the wing, with Juan Mata on the opposite side, as Henrikh Mkhitaryan took the number 10 role.