TORONTO -- Serena Williams made a winning return to the National Bank Open on Monday, defeating Nuria Parrizas Diaz 6-3, 6-4 in the first round. The victory is Williams' first singles win since the 2021 French Open. She will face either Belinda Bencic or Tereza Martincova in the second round. 

Williams is playing her 10th National Bank Open. She made her main-draw debut 22 years ago and has won the title in Toronto three times. In her last appearance, she made the final in 2019, where she was forced to retire against Bianca Andreescu. 

Williams was tested and resilient: The last time we saw Williams on the court was in a grueling first-round loss at Wimbledon to Harmony Tan. In a match in which she was seemingly in control of, Williams failed to close out the win despite twice leading by a break in the final set. But it was her first match in a year. 

Against Parrizas Diaz, she showed she had learned her lesson. Despite the seemingly perfunctory score line, the Spanish lucky loser did not make it an easy day for the 23-time major champion. Over 1 hour and 57 minutes, Parrizas Diaz found ways to test the American's patience and rally tolerance. Williams refused to take the bait. 

Williams opened the match with a quick 2-0 lead before Parrizas Diaz broke back and leveled at 2-2. The two traded serves until Williams broke to 5-3 and closed out the set in a protracted service game, converting on her fourth set point. 

Williams' serve comes through: Williams was broken just once in the match, with that break coming early in the second set. But she refused to let Parrizas Diaz entertain any notions of a comeback by snuffing out six break points across three service games in the second set. 

The most critical game of the match came with Williams serving at 3-4 in the second set. In the longest game of the match, Williams and Parrizas Diaz traded points in a nine-deuce game, which saw the American save four break points before finally holding. 

Despite having taken care of her serve more efficiently in the set, the Spaniard capitulated in the next game. Williams broke on just her second break point of the set and then closed out the win. 

Williams finished the match with 32 winners, including seven aces, along with 29 unforced errors. Parrizas Diaz hit 25 winners to 18 unforced errors. Williams saved seven of the eight break points she faced in the match. 

Williams should take a big boost of confidence: Before Toronto, Williams spent the week in Washington, D.C. on the practice courts at the Citi Open. It was evident from the tournament's social media that she was putting in the hours in challenging physical conditions. 

That work paid off immediately in her Toronto win. Williams was willing to trade measured blows from the baseline before choosing the right shot to unleash on. That rally discipline is when Serena is at her most dangerous, and it only comes when she's feeling confident in her physicality.