Arsenal manager Arsene Wenger denied there was a rift between the Chilean and his team-mates, but admitted the uncertainty over his future has affected team morale.
However, Wenger is not too concerned about the malaise Mkhitaryan is now enduring - he only has one league goal all season - and will work with his new recruit to avoid a repeat.
Along with Chelsea, United have the stingiest defence in the division and Smalling credited Mourinho's work in forming that solid base following the 1-0 win over the Clarets. "I must say he's a player who has all the attributes". Yet having run United close at Turf Moor, goalkeeper Nick Pope is confident their fortunes will change if they maintain their good performances. I remember the first time I seen you play for Udinese Calcio hoping one day I'd see you in the famous United shirt lighting up the Theatre of Dreams.
"He's a very professional player who has been committed until the last minute", Wenger said. "Now that I'm here, I'll do my best for this club to create history", said Mkhitaryan.
United, who have not won the Premier League title since 2013, are second in the table but trail Manchester City by 12 points - a gap that looks impossible to breach even with four months of the season to run. He will complement the striker Romelu Lukaku.
His move to United was celebrated in his homeland, where fans on social media lauded the Red Devils' "winning" mentality, in contrast to the paucity of recent success at Arsenal. Sanchez could make his Premier League debut at White Hart Lane against Tottenham tomorrow week. A bid of £45 million has been rejected but Arsenal are reportedly prepared to spend more than the £52 million they spent to bring Alexandre Lacazette to the club over the summer.
The Kogi state-born coach, who made this known in Lagos on Monday after the training session, said the move became necessary to create the right tactical balance for the team ahead of the competition.
Arsenal are understood to have made an opening offer of £44m for the worldwide who chose to play for Gabon rather than France or Spain which he would have also been eligible for.
Sanchez had attracted interest from Pep Guardiola's Manchester City before joining United.
As the saga played out former Arsenal defender Martin Keown called Sanchez "the biggest mercenary in football", while another former Gunner Ian Wright said in December the Chilean had "clocked off".
"I believe that at this club it's possible to achieve anything".