PARIS, France - Former champion and No.11 seed Garbiñe Muguruza survived the longest women's match of the French Open's first two days on Monday with a 7-5, 4-6, 8-6 victory over Slovenia's Tamara Zidansek.

In a match that lasted a minute over three hours on Court Simonne-Mathieu, the 2016 champion battled back from a 3-0 deficit in the final set to earn victory in the sixth-longest match overall on tour this year.

So far, the contest tops all of the women's opening round clashes in length, with Irina-Camelia Begu's 6-4, 4-6, 6-3 Sunday win over Jil Teichmann clocking in second at two-and-a-half hours. 

In all, Muguruza ultimately needed to win in extra games in the final set after leading by a set, and a break twice in the second. 

"Definitely, [it] was very difficult first round... I know she was playing amazing tennis since the first set, so I just knew that just have to wait for my opportunities," Muguruza said after the match. "I was just trying to stay calm until I saw the chance, and then I went for it." 

After falling behind 3-0 in the opening set, thanks in part to a marathon game in which she was broken after nine deuces and seven break points, the Spaniard won five straight games, but ultimately needed two opportunities to secure a one-set lead.

Never reaching set point in her attempt to serve out the opener at 5-4, she nearly saw Zidansek rally again the second time around, but secured her third set point after opening up a 40-0 lead in the set's final game.

In the second set, the World No.15 saw her break leads come by virtue of winning Zidansek's service games at 1-1 and 3-3, but was broken back each time.

Muguruza was unable to make it a trio of breaks, which would've given her the opportunity to serve out the match in two sets, as Zidansek saved two break points herself to edge ahead 5-4 - and the 22-year-old sent the match to a decider with a fifth break of Muguruza's serve for the match.

"It's always like little details at the end between the great players and the good players," she added. "Especially in first rounds, you can always have surprises. You can always not feel great. Then your opponent, you know what? She's playing great and she wants it as much as you, and you're out.

"It's really there is no more a relaxing match or a feeling that you have it under control, because it's really, really the level, it's very similar."

A winner at the WTA 125 Series event on Bol, Croatia - typically held in the second week of the French Open's traditional spot in the calendar - in each of the past two years, Zidansek showed her clay-court prowess as she moved into the ascendency in a final set that itself lasted over 70 minutes. 

A three-game swing went each player's way, and the Slovenian kept herself in front thanks in part to clutch play when even: she saved three break points at 3-3, and another at 5-5, but ultimately surrendered serve from 30-15 ahead in the game that proved to be decisive. 

"It's a good win. In the end, you're out there and it was a tough battle and you manage to get the win, so it feels great," Muguruza concluded.

"It's definitely a challenge physically with the conditions and such a long match. But I'm happy. It's always tough the first rounds."

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