The United boss spoke to the press after the emphatic 4-1 win at Old Trafford.
But when he walked in to the press room, he asked: “No water? Are we saving money for January?.”
Mourinho had just watched his side dismantle Claudio Ranieri’s struggling Cottagers.
Ashley Young opened the scoring before Juan Mata and Romelu Lukaku put United in a commanding position going into the half-time break.
Aboubakar Kamara pulled one back for the visitors from the penalty spot but Marcus Rashford wrapped up the three points to cap an excellent individual display that also saw him grab two assists.
Mourinho told TV reporters he was delighted with his side’s display moments before making his joke to the written press.
Ironically, reports claim he is set to spend big in the January transfer window to turn around what has been a disappointing start to the season – despite their impressive victory on Saturday.
However, Mourinho was keen to concentrate on the Fulham display.
“The first half was really good. We gave no chances to Fulham,” he said.
“We were strong, aggressive and intense. At times it was beautiful football. The first half was perfect.
“The second half was Ranieri’s fault. He made two changes that improved his team and gave us problems that we didn’t have in the first half.
“I also think there was some fatigue in some of my players. A few factors made the second half not as good as the first.
“We were intense without the ball and with the ball. Without the ball we pressed, we kept Mitrovic away from goal.
“With the ball it was simple, one or two touches. We were really good.
“We needed it. The last three matches we didn’t lose, but didn’t win.
“Now we have two away matches, then two at home. Let’s see if we can get more points from those matches.
“The players have shown they can be a better team than they are. When there is solidarity in the team, everyone giving their maximum, you attract more positive things.”