Manchester United will be playing Saint-Etienne in the last-32 and Mourinho has said he will not be starting Luke Shaw.
The last time the defender featured for United, was in the FA Cup 4-0 win over Wigan Athletic and his last League appearance was in October.
And Mourinho doesn’t seem ready to bring him him back into the fold as he is sticking with the back four he used in the 2-0 win over Watford.
He told reporters: “He’s not playing tomorrow because my team is playing well and I am happy with my back four, and I’m going to repeat Valencia, Bailly, Smalling and Daley Blind.”
United host the Ligue 1 side in the Europa League last 32 first leg and, despite the potential for fixture congestion, Mourinho is adamant they will not “throw away” the competition.
He continued: “If you ask me if I want to beat Saint-Etienne and progress I say ‘yes’. We don’t throw away competitions. It’s harder that the match against Manchester City is postponed.
“If we win against Blackburn, the match against Southampton will be also postponed. In case it happens, it’s going to create many, many, many, many problems.
“Playing Thursday, we have never got a Monday fixture to have an extra day of rest. I know for example that Middlesbrough will be played at Sunday 12:00 so if we progress and get a difficult match we then have to play Middlesbrough on Sunday at 12.
“It’s difficult also in the Premier League because others don’t have games. Liverpool only play Premier League, Chelsea play Premier League and FA Cup.
“We want to progress, tomorrow we go seriously and Sunday against Blackburn we go seriously too.”