A Baron, a Count, a Duke and an Earl met at a jousting tournament. In the first round, two met in the first joust, and the other two met in the second joust; the two winners from the first round met at the second round for the final joust. After the jousting, they declared:

Baron: I beat the Earl.

Count: I faced both the Baron and the Duke.

Duke: I didn't make it past the first round.

Earl: At the first round, I lost to the Duke.

I knew how many were knights, and how many were liars (though not who was what) but that wasn't enough to know what jousts there had been.

However, I happened to know that a certain joust had taken place (though I didn't know who won and if it had been in the first or the second round) and that allowed me to know every result.

Can you deduce this?