Yes, looks like I just can't practice in single mode for half an hour and jump right into online races and expect to win ay.
Incidentally, I'm experiencing some sort of steering lock during online races. Unfortunately, it happens quite often for me when in online mode - my kart doesn't respond sometimes when I try to steer left or right and thus continues driving straight into a wall or off the track. Very frustrating. Is there something I can do to amend this or is it a glitch/bug?