President Joe Biden is planning to meet Saturday with Chinese President Xi Jinping during a trip to Lima, Peru, according to White House officials, in what amounts to a final meeting between two leaders of superpowers amid a period of significant transition that could alter that relationship.

It remains unclear why the Chinese president has failed to attend talks with Pacific-rim leaders in Peru a day after opening a new megaport north of Lima.

President Joe Biden will meet for a final time this week with Chinese President Xi Jinping as he prepares to hand over power — and the reins of the world’s most consequential bilateral relationship — to president-elect Trump in January.