Manchester City striker Sergio Aguero unsure if he is fit enough to start against Chelsea

Chelsea's hopes of laying down an early-season marker at the Etihad Stadium have been given a boost after Manchester City striker Sergio Aguero admitted he may not be picked for Sunday's Premier League showdown.

After Argentina's Copa America run in Chile, Aguero, the Premier League's top scorer last season with 26 goals, was given an extended break and missed most of City's pre-season campaign as a result. The ex-Atletico Madrid star was omitted from the starting line-up as City eased to a 3-0 win over West Brom in their opening game of the season, but did come off the bench for the final 27 minutes.

Manuel Pellegrini chose Wilfried Bony to lead his attack at The Hawthorns and Aguero admits it would not be a surprise to see the manager opt for the Ivorian again, acknowledging he is still to prove his fitness.

"Whether I start or not remains to be seen," Aguero told City's official website. "I am trying to get there and be in top condition, but arriving for pre-season later having taken part in the Copa America with Argentina means I need some additional time. With the whole season in mind, what matters the most is that I get in top form and don't take any risks."

Pellegrini is not the only Premier League manager to have handed an extended break to players who competed in the Copa America. Aguero's compatriot Marcos Rojo missed Manchester United's season opener against Tottenham Hotspur and is also likely to sit out of Friday's match against Aston Villa. Louis van Gaal confirmed in his press conference on Thursday the defender is doing double training sessions in order to hasten his return. Arsenal star Alexis Sanchez, part of the Chile side that beat Argentina in July's final, also missed his side's first game of the season but is in line to return against Crystal Palace on 16 August.