"It's a setback but not serious," Benitez said.
The former England skipper has been dogged by a knee problem this season, returning to action in January after two months out.
Benitez said their Czech Republic goalkeeper Petr Cech and Senegal striker Demba Ba were both available after pulling out of midweek internationals through injury.
Ba suffered a broken nose in the 3-2 league defeat at his former club Newcastle United last weekend and has been training in a protective mask.
Third-placed Chelsea, seven points behind Manchester City and 16 adrift of leaders Manchester United, have won only three of their last 10 matches in all competitions.
Benitez said that, while he was happy enough with recent displays, the Londoners needed to be more clinical and not let leads slip as they did against Newcastle.
"We could win all the games we didn't win," he said.
"It's a question of sometimes doing the right things at the right moment, a little bit of luck, being more clinical and not making mistakes in defence, but the team is doing well in terms of performance."
The Spaniard said he would continue to alternate between Ba and Fernando Torres up front, with Chelsea set for their Europa League bow against Sparta Prague next week.
"I am not rotating because I want to. We have to do it,' he said.
"Demba Ba cannot play Europa League, we have to manage them both and see and I have to decide.
"If we can play both sometimes we will do it but with the players behind it will be difficult so we have to play one or the other, and it depends on each game."
Chelsea are still without Victor Moses and John Obi Mikel who will line up for Nigeria in the African Nations Cup final this weekend but playmaker Eden Hazard is available after suspension.
The Belgian has served his three-match ban for kicking a ball boy which earned him a red card for violent conduct in the second leg of the Capital One (League) Cup semi-final defeat by Swansea City on Jan. 23.
Hazard scored for Belgium with an early penalty in their friendly win over Slovakia in midweek.
Brazilian David Luiz, who featured in his country's loss to England at Wembley on Wednesday, is also back in Benitez's plans after missing the club's last three games with a calf injury.
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