Having been 2-0 down after two errors from new goalkeeper David de Gea, United fought back to win 3-2 at the death.
“This shows who the best team is – all game we dominated,” Rooney told BBC Radio 5 Live.
“The young lads made the difference – Danny Welbeck, Tom Cleverley, Phil Jones, Chris Smalling – they were all outstanding,” he said.
“I think this was a footballing lesson,” he added on Twitter.
