I think that was actually the first time I saw Tennant. And I didn't realise that Crouch jr. and tenth Doctor were played by the same actor untill later when I was checking Tennants bio on the Wikipedia. Quite a suprise.
Then again I was also suprised when I saw Dumpledore killing cowboys, stealing cattle and ruling a small town with his iron fist in "On the range."
Just goes to show that good actors can play different types of roles.