Manchester City striker Sergio Aguero needs a scan to determine the extent of a knee injury sustained during Sunday's thrilling 3-2 win against Southampton.The Argentina striker, 24, was carried off on a stretcher after collapsing following a challenge with Nathaniel Clyne after eight minutes.He attempted to get to his feet only to drop to the turf once again.Manager Roberto Mancini said: "At the moment we don't know. We need to wait for the scan in two days."Aguero scored the winning goal in the 3-2 victory over QPR on the final day of last season to secure the Premier League title.After joining in a £38m deal from Atletico Madrid last summer, he scored 23 Premier League goals in his debut season.Aguero, who was replaced by Edin Dzeko, started the match with Carlos Tevez in attack and Mancini also has Mario Balotelli to call on as a striker.Earlier this month, Mancini admitted defeat in his pursuit of Robin van Persie, who has subsequently joined Manchester United.