Before each day’s play at the U.S. Open, Steve Tignor will preview and predict must-see matches to keep an eye on.

Karolina Pliskova vs. Ana Konjuh

Head to head: First meeting

Kon-juh dig it? The 18-year-old Croat is coming off a statement match vs. Agnieszka Radwanska; not only did she beat the fourth seed in straight sets, but she hit 38 winners to Aga’s nine. But Pliskova wasn’t too shabby herself in saving a match point against Venus Williams and fending off 23,000 fans in the process. Konjuh and Pliskova have never played, but the Czech, at No. 11, is ranked 81 spots higher. The 24-year-old Pliskova is in her prime, and her quarterfinal appearance here is long overdue. She has the serve and the laser ground strokes to beat anyone on a given day; but those lasers, hit flat and low and fast, are every bit as low-percentage as they sound. Konjuh is less experienced, but her firepower comes with a little more margin. That may help on a stage that’s unfamiliar to both.

Winner: Konjuh

Andy Murray vs. Kei Nishikori

Head to head: Murray leads 7-1

These two masters of the backcourt have collided at big events this year; they played in Davis Cup early in the season, and at the Olympics last month. Murray has won both times, once in epic five-set fashion (Davis Cup), and once in routine, straight-set fashion (Olympics). Murray also leads their head to head 7-1, and is coming off one of the most brutally efficient performances of his career against Grigor Dimitrov. Nishikori, a 2014 finalist here and a tougher out in general, should offer a stiffer challenge. He could even win. But it’s hard to think of a logical reason why.

Winner: Murray

Serena Williams vs. Simona Halep

Head to head: Serena leads 7-1

As with Murray-Nishikori, this is a matchup of two excellent players, with a head to head that’s 7-1 in favor of the higher-ranked star. Aside from that one win, in 2014, Halep pushed Serena on hard courts in Miami and Cincy last year. She’s also playing some of the best tennis of her career at the moment; since Wimbledon, she’s won two titles and 17 of 18 matches. Is that enough confidence to make it 18 of 19 against Serena? If Halep is going to beat her, this would seem to be the time and the place, but she’ll need to avoid hitting too many of her floating second serves to do it. Serena, who makes history with every win these days, has looked pretty good, too.

Winner: S. Williams

Stan Wawrinka vs. Juan Martin del Potro

Head to head: Del Potro leads 4-2

The night session closes with a heavy-artillery assault between Del Potro, the man with the game’s most powerful forehand, and Wawrinka, the man with the game’s most powerful backhand. The two have aimed their missiles at each other just once since 2012, under the roof at Wimbledon earlier this year, a match that Delpo won with surprising ease. Look for Stan, who was disappointed in his performance that day, to try hard to redeem himself in Ashe. He also saved a match point against Daniel Evans earlier in the tournament, which tends to make a player more relaxed in later rounds. There has been magic in Delpo’s racquet over the last month, but it has to run out at some point, right?

Winner: Wawrinka