The 18-year-old shone for Leeds against Bolton on Saturday afternoon.
The Leeds United midfielder starred as the Whites beat Bolton 2-1 in the fourth round of the FA Cup.
And the former Leeds forward was pleased with Cook's energy and creativity, as the playmaker flourished ahead of the more defensive Toumani Diagouraga and Liam Bridcutt.
Whelan told the BBC: "Lewis Cook was everywhere and he was creating all the time. That’s the energy that he can bring to a football side."
The good news for Leeds fans is that Cook's response was unequivocal when asked if he'll still be at Elland Road next Saturday.
Indeed, the 18-year-old says he's 'definitely' staying at Leeds and Steve Evans can therefore look forward to at least half a season more of the teenager's creative abilities.
Judging from the Sam Byram saga, interest will certainly increase in Cook should he continue to perform. However, perhaps Leeds can enjoy success next season - which could be enough to keep the midfielder on board.