The judo scene starts off with Dominik and Aleks being paired to fight each-other by their instructor. The two then bow to one-another and grin knowingly in the light of the events of the last 24-hours (the kiss, the flirting in class, ect).
Then the two go on to fight. Aleks (being a higher belt than Dominik) wins three *rounds* before Dominik becomes really determined to win. So instead of Aleks making the first move, Dominik straight-out lunges for him, and the two fall to the ground, Aleks on top.
Aleks pins him down, and they wrestle for a bit, and (I think) Dominik struggles to fight his sexual-excitement (this explains his panting).
He clenches his eyes closed, as he loses the battle - there’s nothing he can do to stop his erection pressing against Aleks. Really I see this as a declaration of his love for Aleks, but instead of most declarations like this, he didn’t have a choice not to tell him.
He pressed against Aleks - it feels good, and (it is my guess) that he was consumed with desire. He opens his eyes, and looks at Aleks. Almost as if he feels that his affections have been somehow returned.
Nothing could be further from the truth, however. As Aleks looks at him, bewildered and alarmed. Personally, I believe he liked Dominik, and that it is also in this moment that he panicked. This wasn’t playing around anymore, his friend without a doubt had a crush on him.
Dominik’s foot flops down, as all those built up feelings (of both lust and love) have been released. As if everything he’d been hiding for the past few months have been both uncovered and accepted. Dominik doesn’t seem to have understood Aleks’ body language.
To this Aleks smirks (out of nerves and the sheer scariness of the situation, I think). He get off of Dominik, and Dominik looks down to see a familiar bulge. To this Aleks laughs, saying “Bloody hell!”
Humiliated, Dominik is forced to make a swift exit to the changing rooms.