The Sam Querrey-Stanislas Wawrinka match is just about to hit the four-hour mark.

Wawrinka is on serve and holds a 2-1 lead in the fifth set. The winner advances to the quarterfinals.

UPDATE (5:26): Querrey is serving, down 3-2 in the fifth set.

UPDATE (5:37): Querrey is serving, down 4-3 in the fifth set.

UPDATE (5:42): Querrey has tied it up. It's 4-4.

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