Rafael Nadal could not outwit No. 1 female poker player Vanessa Selbst. (VALERY HACHE/AFP/Getty Images)

For the last two years, Rafael Nadal has been honing his poker game as an ambassador for PokerStars -- one of the stranger sponsorship pairings in tennis -- and he even won an exhibition tournament in Prague last December.

But Nadal was no match in a heads-up game against the world-No. 1 female poker player Vanessa Selbst in Monte Carlo last week. It's all for a good cause though, as 5,000 Euros were donated to charity for the event.

Nadal playing poker is always an amusing thought given how demonstrative and fired up he gets on the tennis court. Put it this way: What in the world does Rafael Nadal's poker face look like?

Well it looks like this:

Eyebrow? Check. (VALERY HACHE/AFP/Getty Images)

Sheepish grin? Check. (VALERY HACHE/AFP/Getty Images)

Surreptitiously getting advice from his courtside coach? Check. (VALERY HACHE/AFP/Getty Images)

So close. (VALERY HACHE/AFP/Getty Images)

Keep working on it, Rafa. (VALERY HACHE/AFP/Getty Images)

Highlights from the event below: