Wattimena beat former world champion and current world number one Humphries 6-3 on Friday, just two days after coming back from a holiday in Indonesia.
"I have to be honest: the rest has done me well," said Wattimena during the press conference following his win over Humphries.
"We went on holiday for two weeks and came back Wednesday - it sent me onto the stage with a great feeling.
"The warm-up didn't go as well but once I got on stage I was very focused.
"It went well, so nothing to complain about."
World Championship worries?
Wattimena enjoyed a good World Championship but crashed out in the third round after a 4-2 loss against Peter Wright.
However, the Dutchman admitted to not thinking about it much from his sunbed on the island of Bali.
"I played a good World Championship and a good match against Peter Wright.
"His checkouts were very good. There's not much to reflect on since he played such a good game."
The rest he got from his time off helped him on stage, albeit only for so long. "When I was 5-2 up I did get some nerves, but that's normal.
"The last dart was all-or-nothing and it went in, so that was nice.
"I'm delighted with how I threw tonight, I will take that with me to tomorrow."