In complete confusion, team losing after leading (6-4)

'in complete confusion' is the definition.
(upside-down can mean confused)

'team losing after leading' is the wordplay.
I cannot quite see how this works, but
'team' could be 'side' (both can mean a sports team) and 'side' is found in the answer.
'losing' could be 'down' (down can mean losing a sports match) and 'down' is present in the answer.
'leading' could be 'up' (up can mean winning a sports match) and 'up' is found within the answer.
This accounts for all the letters.
This explanation may well be incorrect...

Can you help me to learn more?