Elina Svitolina continued her triumphant resurgence post-maternity leave with a 7-6(2), 6-4 first-round victory over former World No.1 Victoria Azarenka at the Mubadala Citi DC Open on Monday evening.

Former World No.3 Svitolina took 1 hour and 47 minutes to win two tight sets against two-time Australian Open champion Azarenka, booking her spot in the second round of the WTA 500 event.

"It was really up and down," Svitolina said after her win. "Just have to try to focus every point, try to find your game again. Just try again and try again to come back into the match."

Here are takeaways from the opener:

Svitolina keeps head-to-head momentum: Azarenka had won all of their first five meetings, but Svitolina finally got her first victory in their head-to-head last month, winning a gripping Wimbledon fourth-round encounter via a final-set tiebreak.

More from D.C.: Kostyuk saves match points to beat Andreescu

Svitolina held that momentum early on Monday, winning 11 straight points to post a 3-0 lead. However, a love break for 3-1 gave Azarenka a boost, and she reeled off five games in a row to serve for the set at 5-3.

But the pendulum swung back Svitolina’s way, and she again won three games in a row behind sturdy groundstroke rallies. Svitolina was unable to serve out the set at 6-5, but she swept through the tiebreak to claim the opening frame after just under an hour of play.

Returns dominated the second set: Only one game went to the server in the second set, where Svitolina held for 3-2 with a pair of aces, including one on game point.

Azarenka, who was celebrating her 34th birthday on Monday, went 9-for-9 returning Svitolina's second serve in the second set. But that statistic proved to be in vain as the former World No.1 never held her own serve in the set.

Meanwhile, Svitolina had a 60 percent success rate returning Azarenka's first serve in the second set, and she completed the victory with a forehand winner down the line.

Svitolina back on hard court with aplomb: This was Svitolina's first hard-court match since March of last year when she lost her opening match to Heather Watson at the Miami Open. Directly after that event, Svitolina was off tour for over a year, during which time she gave birth to daughter Skaï.

In her return to hard courts, Svitolina will attempt to match or better the peaks of her clay and grass returns this year. On clay, she won the Strasbourg title in only her seventh event back, and she also made the Roland Garros quarterfinals. On grass, Svitolina upset World No.1 Iga Swiatek to reach the Wimbledon semifinals.

"I just want to give it all now [in] these years that I have left," Svitolina said. "I have this motivation to go for more and just give it all."

In the second round, Svitolina will meet No.5 seed Daria Kasatkina, who beat Elise Mertens 6-3, 7-5. Svitolina has a commanding 7-0 lead in her head-to-head versus Kasatkina, including a win at Roland Garros this year.