Originally Posted by Avles
IMO it's virtually impossible to become "bilingual," and difficult to become even reasonably fluent, by studying a language online or with a tutor.
Your plan might be the best for OP's tennis game but it wouldn't do much for his language skills. It's a question of priorities I guess.
A semester spending 5 hours a day studying Spanish would be extremely productive for his language skills. This is the only subject he would be focused on.