.Manchester United boss Jose Mourinho is frustrated with the Ivory Coast after they refused to delay Eric Bailly's African Nations Cup departure by 24 hours.

Bailly returned to the starting XI in Saturday's 2-1 win over Middlesbrough and Mourinho was hoping he would be available to take on West Ham on Monday as well.

That could not happen without the consent of his national side, who are preparing for the tournament in Gabon, and coach Michel Dussuyer was not willing to take the risk.

United should not be harmed in the short term, with Phil Jones and Marcos Rojo ready to restore their successful partnership after being rested for the New Year's Eve victory and Chris Smalling also fit, but Mourinho is concerned about a lack of numbers at the back.

"Bailly is leaving - he goes to the national team," said a clearly disgruntled Mourinho.

"He has to be with them on 2 January. We asked them for him to be on 3 January but they refused, so he cannot play against West Ham.

"With these kind of decisions they are controlling every second, so for sure they are going to win the African Cup.

"I know I lose Bailly for a month so I'm going to have Smalling, Rojo, Jones...three players for eight matches."

The 22-year-old Bailly has had a hit and miss start to his United career, starting the season strongly before a dip in form and fitness.

He is still delighted to be part of the Red Devils set-up and lavished praise on Mourinho, who enters 2017 on the back of six successive wins.

"He is a great manager, the best in the world," Bailly told Sky Sports.

Bailly called Mourinho the best manager in the world (Getty)

"It is a pleasure to work and learn with him. I hope it continues like this and that I stay at United for a long time.

"I'm truly happy with my team and my team-mates. Little by little, and with more training under this manager, I hope to improve."

Mourinho was without Wayne Rooney and Michael Carrick against Boro and the short turnaround time between matches could mean another game on the sidelines for the Englishmen.