Manager Louis van Gaal has urged Manchester United to be cautious as they closed in on the Premier League's top four after Tuesday's 1-0 win over Watford at Old Trafford. Despite a majority of the first-team players on the treatment table, United drew level on points with fourth-placed Manchester City, who have a game in hand, after picking up back-to-back league victories for the first time since November. 'We have to go step by step, I think,' Van Gaal told British media when asked about his side's top-four hopes. 'We have the same problems as three weeks ago. Players are coming back but still I have to solve a problem every week in my line-up, so when players are coming back, they are not fit enough.' Fifth-placed United, who are on a four-game winning streak in all competitions, travel to face 13th-placed West Bromwich Albion on Sunday, having not lost at the Hawthorns during the Premier League era.