There are plenty of enticing matchups on Day 5 of the US Open. By the end of the day, the second round will be complete, and several big names—as well as a few dark horses—will be looking to make their move. Here’s what we’ll be watching:

[1] Jannik Sinner (ITA) vs Alexei Popyrin (AUS)

Alexei Popyrin has made a name for himself as a giant killer—he’s won two of his last three matches against Top-5 players and 12 of his last 20 against the Top-10. Let’s not forget: it was Popyrin who shocked Novak Djokovic in the third round here at Ashe last year.
But now he faces Jannik Sinner, who is cutting through the draw like a bullet train. The World No.1 owns a 22-match hard-court winning streak at the majors and lost just four games in his first-round win over Vit Kopriva. Can Popyrin slow him down in New York?

[23] Naomi Osaka (JPN) vs Hailey Baptiste (USA)

Naomi Osaka looks more and more like her old self, and her hard-court pedigree makes her dangerous. She holds a 2-0 record against Hailey Baptiste, though both meetings have stretched to three sets. Baptiste, now at a career-high No.47, has had a breakthrough season highlighted by a Roland-Garros run, and she has the tools to push Osaka again. The question: will Osaka’s renewed confidence shine through if the match goes the distance?

Snowbirds on Court 7

Canadian fans will have plenty to cheer for. Denis Shapovalov takes on France’s Valentin Royer, while Gabriel Diallo battles Jaume Munar of Spain. Munar has made big strides on hard courts this year, but Diallo’s booming serve and aggressive game could tilt the balance in his favor.

Felix in Focus

Felix Auger-Aliassime joins the Canadian charge on Court 5, where he’ll meet Roman Safiullin. Safiullin is always dangerous, but Auger-Aliassime will be eager to assert himself and move into the third round.