Heads up I don't think you should worry too much about the flush or straight, he's more likely to have an Ace, pair or two-pair. Still, checking might be the best play because if you bet and he pushes (which would be a reasonable raise with a flush/straight) then what? And if the board pairs on the river and happens to give him trips (or if he was slowplaying a straight/flush), you'll stack him (unless he gets a higher boat of course).
I'd probably check it and then gnash my teeth when the river is the
![The Ten of Diamonds [Td]](https://www.pofex.com/images/smilies/Td.gif)
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