Aguero limped out of the recent win over Fulham and missed our last two games but is back in training and getting close to full fitness.
Walker was taken off at half-time of our FA Cup semi-final as a precaution after feeling a pain in his hamstring but has reacted well to treatment.
And Mendy made his first appearance since the end of January after a long-term knee problem and has suffered no adverse effects.
Pep Guardiola says all three will be assessed after this afternoon’s open training session, but believes they should be fit enough to be involved.
“Aguero feels better. He trained with the team for the first time and he feels better," Guardiola said.
“Now we will train. They make a recovery.
“Kyle feels better, we will see now [how he is], and Benjamin recovered well.
“I think they are contenders for tomorrow.”
Guardiola has praised his players and staff for their efforts so far this season.
City remain on course for an unprecedented Quadruple, with the Carabao Cup in the bag and an FA Cup final to look forward to, at the same time as being in the hunt for both the Premier League and Champions League.
Guardiola says none of it would not have been possible without everyone at the football club pulling in the same direction.
“The quality of club and organisation, and the quality of the players [are the reason we are in a good position],” he said. “You cannot do what we have done without incredible human beings and football players.
“I push my players and staff, every three days, to try again.
“We are there, and we know exactly what we are playing for.”
City’s success this term means we have had to endure a punishing schedule.
We’ve played 51 matches already, with potentially 12 more to come depending on results between now and the end of the season.
Such a gruelling set of fixtures leaves the squad open to fatigue, and City’s somewhat laboured performance at Wembley suggested tiredness could be creeping into the squad.
But Guardiola says Tuesday’s game will be a completely different affair, and expects his side to raise their game in a competition in which the stakes could not be higher.
"I don’t know how fresh we are," he said. "I never know before the game how fresh our legs and mind are.
The mind controls the legs. In the semi-final we could be better but it’s happened.
"This is another competition, we know how tough it is. All eight teams left in are contenders to win.
"This leg, it's a tough opponent we know quite well."
You can follow Tuesday's game with minute-by-minute updates in our Matchday Centre!