As several top teams flatter to deceive in the early stages of the season, the Carabao Cup provides a timely opportunity for otherwise peripheral players to put their hands up for selection.
Emery will look to experiment as Arsenal take on Championship outfit Brentford at the Emirates. United, meanwhile, may be tempted to play it safe as they search for a morale-boosting win at home to Derby County.
Master takes on apprentice as Mourinho looks to knock Lampards side out of the competition following Uniteds disappointing draw with Wolves in the English top flight.
Elsewhere, Liverpool take on Chelsea in the standout fixture of the third round. The likes of Fabinho and Xherdan Shaqiri, both summer arrivals on Merseyside, will be desperate for minutes after underwhelming starts to the season.
Five players who should use the Carabao Cup as a springboard…
Ander Herrera (Manchester United)
Ander Herrera will be desperate to get out on the pitch again after suffering an ankle injury at the start of September which meant he missed Uniteds last three matches.
The midfielder made 27 Premier League starts in Mourinhos first season at Old Trafford but this dropped to just 13 last term – and the signing of Fred could reduce his playing time further still.
Mourinho has confirmed that Herrera is ready for Tuesday nights clash and the Spaniard could be picked as an experienced head alongside youngsters Andreas Pereira and Scott McTominay, with Paul Pogba likely to be rested.
Once a favourite among United fans, Herrera is still to convince Mourinho that he should be a regular starter in midfield.
An assured performance against emerging talent Mason Mount, on loan at Derby from Chelsea, could see Herrera squeeze into Uniteds XI away at West Ham on Saturday.
Jose Mourinho on injury concerns ahead of Derby clash
Ander is ready. Marcos Rojo is the only player who is not available through injury and this is Marcus Rashfords last suspension match.
Jordan Henderson and James Milner may have been worried for their places following the arrivals of Naby Keita and Fabinho in the summer
While Keita has settled into the Premier League without breaking sweat, though, £39million signing Fabinho has had a more frustrating start to life on Merseyside and is yet to make a start for the Reds.
A difficult pre-season raised concerns about Fabinhos fitness levels but Jurgen Klopp claimed earlier this month that the Brazilian was making big steps towards his full debut.
Klopp will be tempted to throw him in at the deep end at home to Chelsea on Wednesday evening. The midfielders experience in the Champions League with Monaco should mean hes not overawed by the occasion.
A strong display in front of the Anfield faithful could give Fabinho a much-needed confidence boost ahead of the stiffer test of the Premier League.
Klopp on Fabinho after Liverpool's win over Leicester
Fabinho could have been in the squad, of course, but its quite difficult to make the squad at the moment because they are all fit. Its good to have the situation as one might need a bit of time, or the others are more used to it. Thats the only reason.
But he will come back. And now we have games every three days, and he has made big steps in the last few weeks.
Xherdan Shaqiri (Liverpool)
Another Liverpool new boy hoping for a start versus Chelsea is Xherdan Shaqiri who completed a £13.5million move from Stoke City ahead of the 2018/19 campaign.
Shaqiri arrived as support for Liverpools all-star front-three of Mohamed Salah, Sadio Mane and Roberto Firmino, but the Swiss will hope, in the coming months, to prove hes more than just back-up.
Klopp claimed his decision to hook Shaqiri off at half time versus Southampton was for tactical reasons and the winger will undoubtedly have been upset by his managers decision.
Shaqiris deflected effort against the Saints also went down as an own-goal – what better way to fire him up ahead of the clash with Chelsea?
The former Bayern Munich man shone in pre-season for Liverpool but is yet to find the net this term. A goal against Chelsea would do him the world of good.
Klopp on substituting Shaqiri at half time vs Southampton
I said to Shaq that I have never taken a player off at half-time after such an influential half but we wanted more control. He wasnt injured.
It was a good performance. We did a lot of work on set-pieces so its pleasing all three goals came from set-pieces.
Shaq is a fantastic boy. The free-kick was outstanding. He tried everything and he is a good player to have. Great offensively, needs a little work defensively.
Alvaro Morata (Chelsea)
Despite a scintillating start at Chelsea, Alvaro Moratas Chelsea career appears to be at an impasse.
A crucial 81st-minute winner in Chelseas second match of the season against Arsenal provided hope but the Spaniard hasnt scored since and Olivier Giroud has shown more to impress new manager Maurizio Sarri.
The likes of Eden Hazard and Willian look far more comfortable behind the unselfish Giroud. However, without a centre-forward scoring regular goals for the Blues, they are unlikely to battle for trophies this term.
An improved performance against Liverpool in the Carabao Cup could persuade Sarri to start Morata again against the Reds just four days later in the Premier League.
Theres no doubting that Morata has the talent, but the striker must ensure that a frustrating opening to the campaign doesnt turn into an unfulfilled career at Stamford Bridge.
Sarri after Morata's unconvincing display vs PAOK
Alvaro has to gain confidence with one, two three goals. I am not able to give him confidence.
In this match he had three or four opportunities. He was unlucky. I hope for him in the future I can help him. But the confidence can come with goals. Maybe two goals in two matches, I dont know.
For the first time in this season he was ready in the box. He was on the ball and was active.
Henrikh Mkhitaryan (Arsenal)
Henrikh Mkhitaryan started Arsenals opening two matches of the season but a 2-0 defeats to Manchester City followed by a 3-2 loss away at Chelsea was hardly the start the Armenian had hoped for.
Many have questioned whether Mkhitaryan and Mesut Ozil play together in a Unai Emery team built around pressing the opposition.
The former Manchester United playmaker picked up an ankle injury in Arsenals Europa League victory over Vorskla Poltava but is available for selection for Wednesdays Carabao Cup test at home to Brentford.
Ozil, who played the full 90 minutes against Everton at the weekend, is expected to be rested and Mkhitaryan will be desperate to prove he can be Emerys main man in midfield.
A strong performance could see him sneak back Arsenals XI as they look to leapfrog Watford with a victory over Javi Gracia in the Premier League on Saturday.
Paul Merson on Unai Emery's dilemma with Mkhitaryan and Ozil
He hasnt got the players to have a 20-yard gap between defence and attack, working hard. Ozil and Mkhitaryan are not those type of players.
If you were building a team tomorrow, youd want to play a high pressing game, work as a team, not to have gaps between the lines, and youre not buying Ozil and Mkhitaryan.
If you go the Arsene Wenger way, wanting to play entertaining, free-flowing, great football, then Ozil and Mkhitaryan will walk in any team in the world.
But they will not get in teams that want to press!