The former Barca star forward has scored 28 goals this season for the club in all competitions, but his time in Paris has been marred with reports of rift with fellow striker Edinson Cavani and manager Unai Emery.
The Barcelona forward had to shell out a lump sum amount to get the tax authorities off his back a year ago.
Ronaldo teed up Lucas Vazquez on the hour mark before completing his hat-trick four minutes later and adding a fourth in stoppage time. His only others during the entire first half of the La Liga campaign was a double (including a penalty) in a 5-0 at home to Sevilla in early December. "We have worked well this week and we are looking forward to it", he said. His opener, in that game at Old Trafford, wasn't the finest - with the ball squirming through the wall and beneath Shay Given - but served as further evidence that Ronaldo with a set-piece in his grasp was to be feared. "He's always practising", Ferguson said.
Ronaldo made rapid progress in the academy and was handed his first-team debut for Sporting at the age of 16 by Laszlo Boloni, who was impressed with the teenager's dribbling ability. A killer pass from Michael Carrick found Rooney, who laid it off to Tevez, who passed to Ronaldo's feet.
Tevez bagged United's sixth in the 90th minute as United went back to the top of the table.
He has curbed those rumours with his recent displays, as he chases down a sixth Ballon d'Or and more major honours, but Scolari says Ronaldo is intrigued by opportunities in Asia.
Ferguson's challenge that summer was keeping Ronaldo.
- Of course there is a before and after, I think that when you win this competition, when you raise this trophy, you reach the highest point of your career and obviously you will be seen differently in the club where you won it.