Wayne Rooney is facing a straight battle with Manchester United team-mate Henrikh Mkhitaryan for a place in Jose Mourinho's starting XI; a battle which will commence in their Europa League tie against FC Zorya Luhansk on Thursday.
The 30-year-old was dropped to the bench for Saturday's 4-1 victory over Leicester City but is likely to come back into the frame for the low-key match at Old Trafford. It will be the perfect opportunity for Rooney to find his form, something he has failed to do under Jose Mourinho so far.
It is not just Rooney's poor form that is keeping him on the sidelines but the manner of United's victory over the reigning Premier League champions.
With Mata in Rooney's favoured No.10 role, the team looked much more dangerous in attack, suggesting the club captain had been holding them back in their defeats to Man City, Feyenoord and Watford.
After just one game, it is clearly too early to tell whether Manchester United are better off without Rooney on the field and the door is open for him to return, but he must first prove more valuable than Mkhitaryan.
The Armenian has been on the fringes of the squad since his £26m move from Borussia Dortmund in the summer but, according to Manchester Evening News, will also be looking to convince Mourinho against the Ukranian side.
Both will start the game but only one slot is likely to be up for grabs for the weekend's game against Stoke City. It means Rooney will have to outplay his own team-mate in order to stand a chance of starting in their next Premier League fixture.
Mata, however, is still favourite to start against the Potters after he impressed against Leicester. The Spaniard scored Manchester United's second goal of the game, which was also the only one to come from open play, the other three coming directly from corners.
It is that same role that represents Rooney's biggest opportunity to get back into the team. Zlatan Ibrahimovic has established himself as the club's No.1 striker while Marcus Rashford is arguably second-choice.
Mourinho has already dismissed the idea of Rooney playing in a deeper midfield role, leaving the position behind the striker as the only viable one.
Speaking in July, Mourinho told reporters: "Maybe he is not a No.9 anymore but he will never, with me, be a No.6. He will never be 50 metres from the goal. For me, he will be a No.9 or a No.10, or a number nine-and-a-half, but with me he will never be a No.6, not even a No.8."