Manchester United have completed the signing of French defender Patrice Evra from Monaco on a three-and-a-half year deal. The 24-year-old has come through his medical and United are thought to have paid the Ligue 1 side around £5million for the player, who should now go straight into Sir Alex Ferguson's squad for Wednesday night's Carling Cup tie with Blackburn at Ewood Park. "He is a good age and he is still developing as a player, which is always exciting," said Ferguson. "We have been monitoring him all season and it is fantastic that he is joining Manchester United." Inter Milan were also interested in landing the Senegal-born player, who joined Monaco from Nice in 2002. However, Red Devils chief executive David Gill flew to the principality to clinch the deal on Thursday evening. Although Evra, who will be handed the vacant squad number three, is also capable of operating in midfield, United see their most recent purchase mainly as a left-back. It is a position they have had trouble filling since Gabriel Heinze ruptured cruciate ligaments in September. With Heinze out for the remainder of the season, Evra will be given the opportunity to make a defensive slot his own and try to push himself forward for a recall into the French World Cup squad this summer. The Under-21 international won the last of his five senior caps in 2002, since when he has been ignored by France coach Raymond Domenech. Of more importance to Ferguson will be his contribution to United's cause. Although the Red Devils are virtually out of title contention already and have also been eliminated from the Champions League, Ferguson is determined to secure at least one domestic trophy and finish no lower than second in the Premiership table. As he stated on Monday, he is also intent on building a new side that can be successful in the future and just 10 days since the transfer window opened has already spent £12million following the earlier arrival of Serbian centre-half Nemanja Vidic.