Manchester United thumped Manchester City 4-2 at Old Trafford on Sunday to move four points clear of their cross-town rivals . Louis van Gaal 's men continued their excellent run of form and a Champions League spot looks all but assured now for them after their Manchester derby victory . Manchester City , meanwhile , have gone from joint top on New Year 's Day to 12 points off the leaders and looking over their shoulders at the likes of Liverpool , Tottenham and Southampton . Here are five things we learned from the Manchester derby . UNITED NOW ON COURSE FOR CHAMPIONS LEAGUE . For much of the season United seemed to be in false position , with their performances hardly giving the impression they belonged in the top four . But now - whether by luck or design - something seems to have clicked for Louis van Gaal and United are now playing with a cutting edge and with confidence . A Champions League return now looks likely . Manchester United celebrated a 4-2 win over their closest rivals at Old Trafford on Sunday . CRISIS FOR CITY AND PELLEGRINI . City 's results since going joint top of the Barclays Premier League on New Year 's Day make abysmal reading for a side of their quality . Their run of four league wins in 12 games - during a period in which they also went out of two cup competitions - surely constitutes a crisis for a club with their expectations . The already considerable scrutiny on manager Manuel Pellegrini will increase another notch . Manuel Pellegrini is under increasing pressure after a woeful second half of the season for his team . FELLAINI CONTINUES TO HIT BACK . For much of his first season at United , Marouane Fellaini looked out of touch and possibly out of his depth . That has all changed in the last few months as he has become increasingly important to Van Gaal . The midfielder uses his strength to great effect as United continue to loft the ball forward to him and teams find him difficult to dispossess . Marouane Fellaini celebrates after heading Manchester United into the lead in the first half . Fellaini has been key in United 's recent run of form to lift them into third place in the Premier League . CITY TEAM COMING TO END OF LINE . There can be little doubt that the City team , the core of which has won two Premier League titles , an FA Cup and a League Cup , is coming to the end of its lifespan . Reinvestment is clearly needed in the summer and , on this evidence , the back four would be a priority . Yaya Toure looks on dejected during Manchester City 's thrashing at Old Trafford on Sunday . UNITED NEED TO IMPROVE DEFENSIVELY TOO . For all that United went on to dominate the game , City started superbly , reminding everyone of the quality they do still possess . They troubled United repeatedly at the back , where the central defensive partnership of Chris Smalling and Phil Jones again looked vulnerable . Former Manchester United manager Sir Alex Ferguson watches the game from the stands at Old Trafford . Ferguson was all smiles after Manchester United 's victory , as was singer Mick Hucknall ( left )
Manchester United beat Manchester City 4-2 at Old Trafford . Win moved United 12 points clear of their cross-town rivals . City went from joint top on New Year 's Day to four points behind Chelsea . Marouane Fellaini continues his rebirth in the last few weeks .