The Three Lions struggled to break down Denmark in a friendly on Wednesday but improved slightly when the Manchester United forward was withdrawn, scoring the only goal through Daniel Sturridge.
With Brazil now firmly on the horizon, Rooney is well aware that everyone will have to fight for a place in Roy Hodgson's plans.
"It's the last squad before the manager names his 23-man squad [for the tournament] so there's 29 of us here and we all wanted to show what we can do," he told Sky Sports.
"That goes from me to everyone else. We all still want to show the manager what we can do and I'm sure the manager's got a bit of thinking to do now."
Southampton's teenage left back Luke Shaw was introduced at halftime against the Danes for his senior international debut and Rooney was impressed with the youngster's performance.
"He's done really well," the 28-year-old enthused. "You can see he's confident on the ball, he's a good athlete, he's quick.
"He's done really well so it's down to the manager. He's got some tough decisions ahead of him but that's what he's here for - to make those decisions."