It followed defeats in the finals of both events the previous year, suggesting Williams is feeling the pressure.
Having won only three of their opening 12 league games, a run that led to the departure of Mauricio Pochettino, they have won four out of five under Mourinho to climb to fifth and have reached the last 16 of the Champions League.
On Tuesday, they paid a visit to Canada House, in London, to thank officials for the hospitality shown to them while they were there.
After a seven-match winning streak in the league they have lost four of the last five and suddenly their place in the top four is under threat.
"I just did some simple make-up," he said, adding with self-deprecating humor, "If you say that I had plastic surgery, the way I am now is probably a plastic surgery failure."
The history books have it more often than not that if a team is top when the turkey dinners are handed out, then they will celebrate again with the title come the end of the season. Not always.
He added, "We have Nadal, Djokovic, Federer, who are there, and have always been there. And what I need to do is go the extra mile and surpass them and that's going to be the biggest challenge for next year, I need to surpass one of them in order for me to finish in the top-three next year."
His move brings an end to his five-year spell with Salzburg, whom he joined from Cerezo Osaka in January 2015.
Champions League debutants Atalanta continue their adventure against two-time former finalists Valencia, who knocked out Ajax
"I don't deny that a good player has his commercial value, but if he can't meet the requirements on the field, he has no value," Dong said.
The side who won the European Cup twice in a row under Brian Clough impressed with a fourth-place Christmas finish in 1994-95, but they have been some distance from the top of the tree ever since. Now the club finds themselves in the middle of the Championship where they have been for much of the last decade.
Holders Liverpool will return to the scene of last season's Champions League triumph after they were drawn against Atletico Madrid in the last 16 of the competition on Monday.