Manchester United boss Louis van Gaal has warned his players that Champions League qualification is still not assured despite holding an eight-point gap over Liverpool after Saturday 's results . Following a comprehensive 3-1 victory against Aston Villa , Van Gaal sees next Sunday 's derby against Manchester City at Old Trafford as important in the battle to finish runners-up . But having been given the task of qualifying for the top-four when he replaced David Moyes last summer , he is not letting complacency risk success , though Liverpool 's 4-1 defeat against Arsenal on Satuday lunchtime puts United firmly in pole position . Ander Herrera celebrates with team-mates after scoring his team 's third goal at Old Trafford . 'It is not done yet , ' he said . 'We still have to play everyone else in the top four and the table shows they are the best teams . 'Of course we have a big gap and can afford to suffer a defeat but everything is possible . ' However , van Gaal also sees the derby as an opportunity to push United 's claims for a top-two finish . ‘ I am looking higher up . The derby is a game for the higher places . Chelsea are likely to be champions but you have to keep on putting pressure . Spanish duo Juan Mata and Herrera celebrate the win against Aston Villa at Old Trafford on Saturday . Manchester United 's Wayne Rooney celebrates with team-mates after scoring his team 's second goal . ‘ Manchester City , is a different game to this one against Villa . City shall not come with such a defensive strategy . We have seen the same with Tottenham and Liverpool . These are the matches wehre you can see fantastic matches . There may even be a shock recall for £60million man Di Maria who has been used as a substitute in recent weeks . 'His turn is coming , that I know . But he has to wait for the right moment , ' said van Gaal . Angel di Maria has been used as a sub in recent weeks but he is closing in on a return to the starting line-up . Rooney battles with Aston Villa ace Jores Okore during Saturday 's victory at Old Trafford .
Manchester United beat Aston Villa to secure an eight-point cushion . Louis van Gaal 's side currently sit third a point ahead of Manchester City . Rivals Liverpool find themselves in fifth following their defeat to Arsenal . But Van Gaal has warned his squad it is important to battle till the end .