A hypothetical meeting between Zheng He and Portuguese sailors

What might happen if Zheng He's fleet met an early Portuguese fleet off West Africa?

The chronology must first be altered, and a cautious exchange or negotiation would be more likely than an immediate battle.

Zheng He's voyages and the later Portuguese expansion associated with da Gama and Albuquerque do not overlap. Making the encounter possible requires either a later Chinese expedition or an earlier Portuguese fleet. Once that premise is accepted, the unfamiliar maritime powers would probably investigate one another before resorting to battle. The chronological repair must come before any speculation about diplomacy or conflict.