Manchester City fear captain Vincent Kompany could be sidelined for up to six weeks with his groin injury.
The influential defender was ruled out for at least a month after limping out of City's season-opening Barclays Premier League win against Newcastle on August 19.
Kompany has said he hopes to return inside a month - possibly for the trip to Stoke on September 14, or the start of the Champions League campaign three days later - but manager Manuel Pellegrini has warned he will not be rushed. Pellegrini said: "(There is) nothing new with Vincent.
"Doctors said from the beginning it could last for six weeks. We will see next week how he improves but less than one month is impossible."
On the positive side, fellow central defender Matija Nastasic is fit to start this weekend's clash against Hull.
Having only just recovered from an ankle injury, the Serbian was an unused substitute in last Sunday's defeat at Cardiff while midfielder Javi Garcia filled in at the back.
Pellegrini, speaking at his pre-match press conference, said: "Yes, Nastasic is able to play from the beginning.
"I think that Javi didn't do bad but he normally plays in midfield.
"It is Nastasic's position so I think it is better for the team."
Pellegrini is anxious to get back to winning ways against Hull after unexpectedly slipping up against another of this season's promoted teams in Cardiff.
That match was painted as a rude awakening to the toughness of the Premier League to Pellegrini, but the Chilean is dismissive of such talk.
He said: "I don't need to lose a game with Cardiff to know about the Premier League.
"In football - I know perfectly - it is very difficult in some moments to defend set-pieces.
"It was a bad game that way but we must improve in the next game because, in every league, it is a very important thing.
"I saw Hull's first two games in the Premier League. I thought they played well against Chelsea, especially in the second half.
"I am sure we will have a very difficult team here, also defending well and trying to counter-attack.
"We will have to play a very good game if we want to win."
Suspended striker Yannick Sagbo is the only confirmed absentee for Hull's trip, but the likely return of Stephen Quinn (hamstring) to the match-day squad is good news.
Sone Aluko has warned City - and the rest of the Barclays Premier League - that Hull do not intend to be anybody's "whipping boys".
The Tigers face City at the Etihad Stadium on Saturday, another testing away trip following their season opener at Chelsea.
Hull lost that match 2-0 but responded by defeating Norwich with 10 men for their first top-flight win since promotion to the top flight.
Pellegrini's title hopefuls will be expected to steamroller their opponents -but Aluko does not accept that is a formality.
Indeed, the former Rangers forward feels any team would be wrong to underestimate Hull this season.
"If they do, then they won't do it for long," said Aluko.
"In this league everybody gets watched, scrutinised and the managers do their homework.
"We always try to play football, teams will eventually see that. A lot of people said Hull will definitely go back down, like we'll be whipping boys, but I think people will be surprised.
"There aren't many deficiencies in that City squad but I'm sure the manager has a game plan for us to work on. We can't follow Cardiff's plans so to speak, we have different players, so we have to have our own game plan.
"We won't be starstruck at all. If you go there starstruck you'll definitely lose.
"They won't want to lose to two newly promoted teams but the Cardiff result gives us confidence it can be done."
Manager Steve Bruce echoed Aluko's sentiments, reiterating that Hull would need to play an active role in the game, rather than just park 10 men behind the ball.
He also took some succour from Cardiff's efforts, but realises a City "backlash" to their 3-2 defeat is equally possible.
"We are going to have to play well because we are playing one of the big, big teams in Europe," said Bruce.
"First and foremost you have to defend very, very well but the big thing for us is to take part in the game and pose a few problems if we can.
"All credit to Cardiff, they've shown there is light at the end of the tunnel for all of us."