Azarenka, who smiled and bobbed her head along to music being played during changeovers on Arthur Ashe Stadium court, fired 21 winners to dominate the 16th seeded Belgian in their very first career meeting in a singles match. Azarenka took the very first set after the usually rock strong Belgian sent out a forehand broad for her 13th unforced mistake of the set.

A loose and confident Victoria Azarenka subdued Elise Mertens 6-1 6-0 on Wednesday to advance to the semi-finals of the U.S. Open, where she’ll deal with a familiar opponent in Serena Williams. Azarenka, who smiled and bobbed her head along to music being played during changeovers on Arthur Ashe Stadium court, fired 21 winners to control the 16th seeded Belgian in their first career meeting in a singles match.

Azarenka took the first set after the usually rock solid Belgian sent a forehand broad for her 13th unforced mistake of the set. The 31-year-old Azarenka didn’t let her foot off the gas in the second, running Mertens around the court and sealing the win when Mertens disposed a backhand into the internet on match point.

With the win the 2 time Grand Slam champ Azarenka has advanced past the quarterfinals at a Grand Slam for the very first time given that 2013. The win establish a semi-final face-off with Serena Williams, who beat Azarenka the Belarusian’s U.S. Open finals looks in 2012 and 2013.