Australia's star of the first day at The Oval was lost for words when asked of England's shock decision to call-up unheralded spinner Simon Kerrigan for the dead-rubber fifth Test.
A ruthless Watson ensured a brutal Test cricket initiation for Kerrigan, who was smacked for 28 runs off his opening two overs and delivered some shockers in one of the more embarrassing debuts in recent memory.
A long pause and cheeky grin preceded Watson's response when asked if his eyes lit up when he learned of Kerrigan's selection.
QUICK SINGLE: Watson 176, Australia 4-307 at stumps on day one
"Look, once the toss went up and knowing that he was going to play, I certainly understood what he was going to bowl to me," Watson said of Kerrigan, who had 0-53 from eight overs.
"After the last tour match I certainly had a game plan of what I was going to do and I sort of followed on from that in this innings."
Like most, Watson was surprised by England's bold selection strategy, which has the potential to backfire in the hosts' quest for a 4-0 series win.
With the series already wrapped up, England opted for two spinners at home for the first time since 2009 and also handed a first cap to fast bowler Chris Woakes (0-52).
The pair came in for Tim Bresnan and Jonny Bairstow.
Watson had expected to be facing hulking paceman Chris Tremlett, who is yet to get a look-in this series.
But he wasn't complaining at getting another shot at his new bunny.
"I was certainly expecting him (Tremlett) to play more so than Woakes or Kerrigan," Watson said.
"... Certainly I'm a bit happier not to face a guy who is six-foot-eight bowling balls that are bouncing up into your splice all the time."
Kerrigan's opportunity came as a result of Monty Panesar being overlooked after being fined by police after urinating on nightclub bouncers earlier this month.
But the 24-year-old faces a big ask to ensure his Test career is nothing more than a flash in the pan.
Paceman James Anderson said it was now up to England's players to help restore Kerrigan's confidence.
"The guys in the dressing room have a got a job to do. We have to rally round him and try to keep his spirits high," Anderson said of his Lancashire teammate.
"He has had one bad day but he can come back tomorrow and show everyone what he can do.
"He is a quality player and that is why he has been picked."
Anderson (2-52) was England's best bowler on the opening day, taking the crucial wickets of David Warner and Michael Clarke to move ahead of former fast bowler Bob Willis into second on England's all-time list of Test wicket-takers with 326.