England are appealing Rooney's three-match international ban for kicking Miodrag Dzudovic in last month's 2-2 draw with Montenegro.
But as it stands the Manchester United star will miss the three group games at Euro 2012.
Instinct: Darren Bent was in the right place to score for England in Montenegro
Manager Capello will use the friendlies against Spain and Sweden to look at alternatives and Bent is ready to grab his chance.
The former Tottenham and Sunderland forward did not make the last two World Cup squads but goes into Friday's clash with the world and European champions full of confidence.
Bent has four goals in his last five internationals and five in the Premier League this season.
He said: 'It's a massive week for me. I'm up there with the best periods in my career just as we're playing Spain, the best team on the planet.
'I kind of knew this was going to be a big season for me. The year before big competitions it seems to have gone well for me but then it hasn't paid off. Hopefully it'll be different this time.
'I've never been at the World Cup and we didn't qualify for Euro 2008 but this is a big chance to show everyone what I'm about and I'm looking forward to it.
Deadly double: Striker Bent is full of confidence linking up with the England team after scoring twice in Aston Villa's weekend win over Norwich
'I've never scored at Wembley and would be delighted to break that duck.
'It's a big blow for England Wayne Rooney not being there because you need your world-class players at the big tournaments.
'It's unfortunate he won't be there but if I'm selected I'll do everything I can to help.
Tough test: Fabio Capello's England face Spain
'I'm not sure how England fans perceive me. They clearly see Wayne Rooney as the No 1 but after that it's a free for all. There's one of four players who can do his job.
'It depends on your form at the time.The fans have their views because they watch the games but at the end of the day only one person's opinion really matters and that's Fabio Capello's.
'I feel really confident at the moment. We started off a bit cagey at Aston villa at the start of the season but as we've settled in it has got better.
'It'slike an audition to prove you can play against the tougher teams. It doesn't make me nervous, you just have to think of it as another game.
'At first I thought I had to prove myself more than other players. But now I feel more relaxed because it's the first time in my career that I've played four or five games on the bounce when I've been fit.'
Change of plans: Wayne Rooney's red card in Montenegro has forced Capello's hand and he will have to tinker his line-up against Spain and Sweden
Bent, 27, has 11 England caps and is desperate to put on a show against the world's best team at Wembley.
Headded in The Sun: 'I'm playing as well as I ever have for England. The ball's going in the net and if I keep working hard and keep doing that and proving myself it should be okay.
'I've run out at Wembley for England and in the Carling Cup final for Spurs. It's a fantastic feeling.'
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Source: Daily Mail