Rooney came off the bench to score the winner in Manchester United's 2-1 win over Aston Villa in Sunday's League Cup final and manager Alex Ferguson said that a further knock to his already-painful knee left him in doubt for Wednesday's match.
Rooney, however, said he expected to play. "It's OK, I went for a scan today and it's just a bit of bruising," he told a televised news conference on Monday.
"It's a bit of a rest day today. I should train tomorrow and hopefully play Wednesday."
Sunday's winner made it seven goals from the last eight with his head.
"I've scored a few headers of late," he said. "I've worked on it for the last couple of years now. Delivery this year has been better, my movement and timing on headers have improved and it's all come together."
Rooney also had words of support for John Terry, who was stripped of the captaincy after newspaper allegations over his affair with the ex-girlfriend of his former Chelsea team mate Wayne Bridge.
"John Terry is a leader for our team and although he hasn't got the armband he's still a great player and a great leader and it's been no different since we met up," Rooney said.
"He is a great player, he's been named in the world XI for the last three years and there are no worries about his form."
Rooney declined to comment on Bridge's decision to retire from international duty in the wake of the revelations but said he hoped the Wembley crowd would give Terry a good reception.
"I've been in a team when a few players have been booed at Wembley, it's not nice and it doesn't send the right message," he said.
England are playing African Nations Cup winners Egypt to help prepare for the World Cup group stage opponents Algeria.
"Egypt will be difficult to play against, they've won the African Nations Cup three times in a row and it will be a tough game," Rooney said.
"We want to try to prepare well for the World Cup and this is probably the first step to build on. I'm sure if the manager has got different ideas he'll use them on Wednesday and it will give him a chance to look at a few other players too.
"The last game was Brazil and got beaten deservedly so it's nice to get back playing for England."
Rooney said he had no problem with Fabio Capello's decision to keep the players separate from their wives and girlfriends - collectively dubbed the WAGS during the last World Cup - in South Africa this year.
"If they want to come and support their husband there is nothing stopping them but last time they were all together in the hotel and that was a bit of a problem but I don't think it will be like that," he said.
Rooney said his own wife Coleen would not be in South Africa having recently had a baby."
