Juan Mata is expected to complete his move to Manchester United on Friday after the English champions agreed a fee of 37 million pounds with Chelsea.
Mata, 25, is set to swap Stamford Bridge for Old Trafford after becoming a peripheral figure since Jose Mourinho returned to Chelsea last summer.
The Spaniard had been expected to head to Manchester for a medical on Thursday but a few minor logistical issues meant the trip had to be delayed.
United officials are still relaxed about the situation and hope to complete the formalities on Friday, allowing him to train with his new teammates over the weekend, before being presented to the media next week.
He is expected to make his United debut against Cardiff at Old Trafford on January 28.
Sky Sports News has reported that a third party bid for Mata has been made, and ESPN sources have said Paris Saint-Germain and Atletico Madrid were Chelsea's preferred options for a sale, but the Blues accepted the bid from United after Mata made it clear that Old Trafford was his first choice.
Mourinho already has Eden Hazard, Oscar, Andre Schuerrle and a rapidly improving Willian in his squad to cover the attacking midfield positions, and Chelsea announced on Thursday that they have agreed a fee with FC Basel for Egypt winger Mohamed Salah.
Mata has started only half of Chelsea's Premier League fixtures so far this season -- and just one Champions League fixture -- despite winning the club's Player of the Season award in each of his two full seasons in West London, and that comparative lack of game time has seen him slip down the pecking order for Spain just five months before they begin the defence of their world title in Brazil.
Signing Mata would also provide an ideal tonic for United after a summer in which they failed to land several high-profile transfer targets and in the wake of Wednesday's penalty shootout defeat at the hands of Sunderland in the second leg of their Capital One Cup semifinal.
United boss David Moyes -- whose only major signing of the last transfer window was Marouane Fellaini -- would not field any transfer-related questions in his postmatch news conference but, on Thursday, Arsenal manager Arsene Wenger said he was taken aback by the move.
"I am surprised," Wenger said of Mata, who had been heavily linked with Arsenal before he eventually joined Chelsea and again during the summer. "Juan Mata is a great player and they sell a great player to a direct opponent.
"It opens again a little bit the opportunity of this transfer market because Chelsea has already played twice against Man United. They don’t play against them anymore. They could have sold him last week [before United’s 3-1 defeat at Stamford Bridge].
"If you want to respect fairness, that should not happen. You would want that everyone is on the same level. Chelsea do not do the rules. Maybe the rules should be adapted to more fairness."
Information from the Press Association was used in this report.