RIO DE JANEIRO — Over to you, Usain Bolt, and the bar is even higher than usual.
Michael Phelps and Bolt have been an Olympic one-two punch since 2008 in Beijing, where Bolt emerged to tear up the track while Phelps was already an absolute ruler in the pool.
On Saturday they will overlap briefly once more, with Phelps, now 31, finishing up one of the most remarkable meets of his career, and with Bolt, fast approaching 30, launching his meet with the first round of the 100 meters.
Neither had anything left to prove when they arrived here. Phelps was already the greatest swimmer of all time. Bolt was already the greatest sprinter. But that has not stopped Phelps from pushing himself to more gold medals against new and familiar rivals. And it will not stop Bolt from doing his falsely nonchalant best to hold off old foes like Justin Gatlin and young threats like Trayvon Bromell, who are hungry to chase him down before he sprints into the sunset.
There are rumblings about the Tokyo Olympics in 2020 for Phelps, who came…