By ESPNSTAR.com staff
The former England captain's comments came following United's 3-0 win at Newcastle United on Sunday.
It was a match in which Rooney's all-around presence on the pitch shone through as he was handed a free-role by his manager Sir Alex Ferguson.
"Wayne Rooney produced a master class yesterday [Sunday] to announce he is very much back in business," wrote Shearer in his column for The Sun.
"He was at the centre of Manchester United's best display for some time in the 3-0 win at Newcastle.
"The season started horribly for the player - poor against Everton, dropped, then injured.
"The star of the show was Robin van Persie and Rooney's Old Trafford future was coming under the spotlight.
"But you cannot keep a player of this man's ability down for long.
"Looking fit again and firing on all cylinders, he was everywhere at St James's Park."
Shearer noted that Rooney helped out in defence, was available for the ball from the back, on the wing to cross, and ready to go in behind Van Persie directly through the middle.
"When he is in this mood, he still ranks for me among the best in Europe. His touch, passing and energy made Manchester United tick," Shearer said.
"Perhaps that axeing for the game against Fulham and his time out injured have helped to refocus him.
"He had a great last league campaign but struggled at Euro 2012 and, maybe, was still recovering from that disappointment when he returned to his club for pre-season.
"Boss Alex Ferguson made it clear nobody has a right to be in his team.Rooney effectively had the ball taken off him but yesterday [Sunday] he showed he wants it back for keeps.
"A player of his calibre must be a joy for any manager, as you can play him anywhere in the team and get something from him.
"If he was asked to play at right-back, he would probably be the best right-back as well.
"Played down the middle as an out-and-out striker he is lethal."
United's 3-0 win on Sunday lifted them to second in the Premier League after seven games, four points behind leaders Chelsea.