The Portugal winger is top of the Premier League assists chart in addition to bagging 10 goals in United’s relentless pursuit of the treble.
On Saturday, he set up the Red Devils’ opener by dribbling to the heart of the Cottagers’ defence before exchanging passes with Anderson, then flicking a pass for Dimitar Berbatov to ram home his 22nd goal of the campaign.
It was also Nani’s shot that was turned into the path of Antonio Valencia by Aaron Hughes that completed the scoring, allowing United to cruise home in exactly the manner they would have wished ahead of such a massive week.
They play Chelsea tomorrow in the second leg of their Champions League quarter-final, and Manchester City on Saturday in the FA Cup semi-finals.
Nani has not managed to make the PFA shortlist, even though it has been extended to seven names this term.
“I am pretty amazed by that,” said O’Shea. “Maybe because he was still eligible for the young player, people didn’t vote for him for the senior player.
“He is a constant threat. Defenders don’t know whether he is going to go on his left or his right and his combination with Patrice Evra was excellent.”
Five victories from their final six games would be enough to confirm a record 19th league title for United. It is not straightforward given nearest challengers Arsenal and Chelsea are among their opponents, while a tricky trip to Newcastle follows three days after the FA Cup semi-final with Manchester City.
Manager Sir Alex Ferguson will not allow his players to think about anything except tomorrow’s game with Chelsea.
“It is a classic cliche but we are just chalking off one game at a time,” said O’Shea.
“The good thing is we feel so confident, especially at home.
“We have only dropped two points at Old Trafford this season and that day, against West Brom, was very disappointing.
“It would be very special if we could finish off the season keeping that record.”
Having made eight changes to his starting line-up on Saturday, a similar number can be expected tomorrow from Ferguson.
On seven of their last 10 meetings at Old Trafford, United gained a result that would put them into the last four, while they have never lost a two-legged Champions League tie having won the away leg first.