Dries Mertens scored a hat-trick as Napoli thrashed Bologna to keep alive their slim hopes of winning Serie A.
Had Napoli lost, Juve could have won a fifth straight title with victory over Lazio on Wednesday.
Victory, achieved without suspended top scorer Gonzalo Higuain, moves Napoli eight points clear of Roma in third.
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Only the league's top two sides will qualify automatically for next season's Champions League, with the third-placed side having to negotiate a play-off.