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 four points clear of their cross-town rivals . City went from joint top on New Year's Day to 12 points behind Chelsea . Marouane Fellaini continues his rebirth in the last few weeks .