Manchester City fear they could be without captain Vincent Kompany until the end of September -- meaning he would miss the Manchester derby and the start of their Champions League campaign.
The Belgium international, 27, suffered a groin injury in the 4-0 win over Newcastle on August 19 and said earlier in the week he hoped he would be back soon after the international break.
However, manager Manuel Pellegrini, whose side face Viktoria Plzen in the Champions League on September 17 and Manchester United in the Premier League five days later, said the club’s doctors fear he may spend six weeks on the sidelines.
“We will see next week how he improves but [for Kompany to return in] less than one month is impossible,” he said.
In the short term, Pellegrini will welcome back fellow centre-back Matija Nastasic for Saturday’s game against Hull.
The Serbian injured his ankle in the pre-season Barclays Asia Trophy final against Sunderland and was an unused substitute for City’s 3-2 defeat to Cardiff on Sunday, but Pellegrini said he would be “able to play from the beginning” against Hull.
Micah Richards, who has missed both league games so far with a hamstring injury, is back in training but will not be in contention to face Steve Bruce’s side.
Pellegrini hopes the England international will be able to step up his bid for a comeback on the training pitch next week.
“Next Monday we will start working with the players who stay here [during the international break],” he added.
With three centre-backs injured, Javi Garcia played in defence against Cardiff and Pellegrini added: “Javi didn’t do bad. He normally plays in midfield but it is Nastasic’s position so I think it is better for the team.”
The Chilean remains keen to bring in another centre-back before the transfer window shuts with Atletico Madrid’s Martin Demichelis his main target.
He said: “Before next Monday we will see what we can do. We have some days to bring someone in.”
While City have been linked with Porto’s Eliaquim Mangala, they have no interest in the Frenchman.