(GUARDIAN) - Manchester United have completed the purchase of midfielder Nemanja Matic from Chelsea on a three-year deal for an undisclosed fee, with an option to extend for a further year.
British media reports have put the transfer fee at £40 million (S$71 million).
Matic's signing represents a significant boost to manager Jose Mourinho after United failed in their efforts to purchase England midfielder Eric Dier from Tottenham Hotspur.
Juventus were also keen on Matic but the player, who turns 29 on Tuesday, preferred a move to Old Trafford and a reunion with Mourinho.
He was a key component of Chelsea's title-winning team in 2014-15 after being brought back to the club in January 2014 from Portuguese side Benfica for £20.75 million.
Chelsea were particularly keen to drive a hard bargain with United after missing out to them over the signing of striker Romelu Lukaku from Everton.
Matic's Stamford Bridge exit had long been expected after Chelsea manager Antonio Conte signed the French international midfielder Tiemoue Bakayoko from Monaco in £39.7 million deal earlier this month.
A picture circulated on United's official Twitter showed Matic in a Red Devils training kit and wearing No. 31, which had been vacant since the departure of German midfielder Bastian Schweinsteiger.
"Nemanja is a Manchester United player and a Jose Mourinho player. He represents everything we want in a footballer; loyalty, consistency, ambition, team player.
"I would like to thank him for his desire to join us because without that, it would be impossible to have him here. I am sure our players and supporters will love him. A big welcome to our new number 31," said Mourinho, in a statement on the club's official website. (www.manutd.com)
Nemanja Matic was equally effusive: "I am delighted to have joined Manchester United. To work with Jose Mourinho once again was an opportunity I couldn't turn down.
"I have enjoyed my time at Chelsea and would like to thank the club and the fans for their support. I cannot wait to meet my new team-mates and to start training with them.
"This is a very exciting time for the club and I am looking forward to playing my part in creating more history for this great club."
Chelsea had left Matic out of their tour to Asia to allow him to finalise a move.
He becomes United's third signing of the summer following a £31 million deal for Swedish defender Victor Lindelof and the £75 million move for Belgian international Lukaku.
The Serbian international could make his debut against Sampdoria in Dublin on Wednesday or in the Uefa Super Cup against Real Madrid next week.