The Argentine striker returned to the selection of the day against Marseille last week and came off the bench, scoring with one of his first touches. However, Guardiola had previously said Aguero would not be fit enough to start the game against United when he fell with gastroenteritis which saw him miss the visit to Old Trafford altogether.
The City manager admitted after the derby stalemate that his side are missing their goalscorer, but he is also reluctant to bring him back too early as other players fight to be part of the squad.
“With Sergio, it’s one step at a time,” Guardiola said. “He had a training session, he was away four months and there are players who, for them, not being in the squad would not be fair to them.
“That’s why sometimes I have to manage the balance of the team. For me, it’s so hard to let Nathan Ake down after being exceptional against Marseille.
“He couldn’t be selected today because there is this rule that there cannot be 19 or 20 players when all the players are available for the team, some are at home.
“I hope Sergio will be back, do more training sessions and as many minutes as possible to come back as soon as possible. ”
Guardiola also preferred John Stones on defense alongside Ruben Dias over Aymeric Laporte, as the French defender on the bench has yet to start a Premier League game since the 2-0 loss to Tottenham last month.
City sit seventh in the Premier League standings ahead of the game, one place behind Manchester United – an unusual occurrence in recent years.
But with both sides having a game in hand over those above and below them, a win at Old Trafford can propel them to the top of the league.
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Tuesday’s game with West Brom will provide them with an opportunity, but Laporte and Ake have been challenged to keep raising their levels if they are to dislodge either of the current pair as center-backs.
“He deserves to be on the team but John Stones and Ruben also deserve to be on the team,” Guardiola said of Laporte. “They have played very well in the last few games and haven’t made a single mistake.
“Aymeric played so well against Marseille and that’s the goal – the team selection. Nathan Ake played extraordinarily well against Marseille but I have to make a selection. They didn’t make any mistakes.
“What they have to do is work harder, work better and the time will come, and when the time is right, perform well. Every player on every team has amazing skills like United, Spurs and Liverpool. But it’s all about your performance. now. At the moment. John and Ruben played brilliantly, so they play. ”