When Zoro saw Kiku's arm fall, he went off and destroyed Apoo.
When Zoro realizes Luffy needs rest, and that Kizaru is still active, and that Saturn has shown up, Zoro will expend whatever energy he needs to wreck Lucci, and then turn to protecting Luffy, since Zoro knows Sanji will take care of Saturn for the moment.
Lucci next chapter: "Heh, your captain is pathetic, losing to Kizaru so quick."
Zoro: "He hasn't lost... he's just taking a break. You're the one who's done for."
Zoro was fine stalling Lucci when it was Luffy vs Kizaru and no Saturn, now, Zoro will get serious.