Choosing between Gabriel Jesus and Sergio Aguero is Pep Guardiola's toughest decision at present with high-flying Manchester City but the star strikers will have to get used to spending time on the bench.

Aguero has 10 goals in 12 appearances across all competitions this season, during which time he has established himself as City's all-time leading goalscorer.

The Argentina star looked on as an unused substitute as Brazilian team-mate Jesus joined him in double figures for the campaign by opening the scoring in Saturday's 2-0 win at Leicester City, which preserved the Premier League leaders' unbeaten record.

This run began with Guardiola using Aguero and Jesus in tandem but it is now a case of one or the other inside in-form wingers Raheem Sterling and Leroy Sane.

"For me it is so tough to leave Gabriel or Sergio out, so tough," the City boss said ahead of Tuesday's Champions League match against Feyenoord, where a better result than Shakhtar Donetsk manage at Napoli will guarantee top spot in Group F.

"But we play with just one striker and I have to change something. There are a lot of games and they have to be ready and prepare well, especially sometimes when they are on the bench and the situation is not good – be ready to try to win the game."

Guardiola made it clear his change of approach in attack is based solely upon losing full-back Benjamin Mendy to a knee ligament injury.

The former Monaco favourite made an instant impression at City with his lightning raids down the left flank, a factor that allowed Guardiola to select a narrow frontline.

Fabian Delph has deputised superbly for the absent France international over the past two months but does not provide the same kind of attacking threat, leaving Sane to supply the natural width.

"In that moment [when Aguero and Jesus played together] we had Mendy and when you have Mendy you [the left-back] play wide and the winger can go inside," Guardiola explained.

"Without Mendy, Delph cannot do that and you have to go wide with Sane. That is the only reason why they don't play together."