Manchester United eased past Saint-Etienne in the Europa League on Wednesday night, but their 1-0 win in France has ended up causing manager Jose Mourinho a number of headaches.

Henrikh Mkhitaryan gave his side an early lead with a smart close-range finish but was then forced off with a hamstring injury. Michael Carrick then followed him after hurting his calf in the second-half, with both now doubts for Sunday’s EFL Cup final against Southampton.

Equally frustrating for Mourinho was the dismissal of his 22-year-old centre-back Eric Bailly, who picked up two yellow cards in the second-half, ruling him out of United’s Round of 16 game.

And Bailly’s dismissal is worse than initially thought for Manchester United.

That’s because the defender, who had been booked twice before the second-leg of the Saint-Etienne tie, was already only one booking short of picking up a one-match suspension for accruing three yellow cards.

Bailly will be forced to sit out the first-leg of the next round (Getty)

So a one-match suspension was triggered the moment he slid in on Romain Hamouma and was booked by referee Deniz Aytekin.

Bailly fouled Hamouma for a second time moments later, resulting in his dismissal, leading many supporters to wonder whether the defender would now be banned for a second game.

However, the Europa League regulations explain that:

"From the first match in the group stage, a player is suspended for the next competition match after three cautions in three different matches, as well as following any subsequent odd-numbered caution (fifth, seventh, ninth, etc.)"

That means that Bailly will serve a one-match suspension while reverting back to two yellows for the rest of the competition – meaning he remains one booking away from a one-match suspension.

All yellow cards are cleared at the quarter-final stage.

Mourinho was not impressed with Hamouma's theatrics (Getty)

After the match, Mourinho was less interested in the legal technicalities and more more interested in criticising Hamouma, who he felt had made the most of both challenges.

“I think the sending off was harsh,” Mourinho commented.

“Hamouma has many good qualities and is a good player, but he enjoyed too much the diving and the simulation, so he gets these situations.