No.12 seed Garbiñe Muguruza overcame both the rain and a last-minute change of opponent as she swept to a second-round spot at the Internazionali BNL d'Italia on Tuesday.

Former World No.1 Muguruza defeated lucky loser Patricia Maria Tig, 6-1, 6-2, in just over an hour, as the Spaniard improved to a superb 22-6 on the season.

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"It was a weird day," Muguruza said in her post-match press conference. "I woke up sunny, had an opponent. Then it turned out I had another opponent and it was raining the whole match. We had a little bit of everything!

"But, Rome, it's such a familiar tournament. I played here so many times, I've had nice matches. I love this clay, the red clay. It's familiar to me. Just looking forward to get as many matches as possible."

Muguruza, a three-time Rome semifinalist (including last year) was slated to face last week’s Madrid semifinalist Anastasia Pavlyuchenkova today, but the Russian withdrew from the event due to an abdominal injury.

Thus, World No.64 Tig, who lost to Christina McHale in qualifying, was put up against Muguruza. The Romanian is an extremely capable customer on clay, having won her first WTA singles title on the surface in Istanbul last year, but could not match Muguruza on the day.

Muguruza won nearly 80 percent of points returning Tig’s first serve and converted six of her eight break points in the clash to romp to victory. Muguruza had 20 winners to 11 unforced errors, while Tig was undone by 24 unforced errors in the affair.

After an early exchange of breaks to 2-1, Muguruza took command from there as a drizzle began to fall. Having surged ahead to 4-1, Muguruza kept pressure on Tig with smothering groundstrokes, and used a deep return to break the Romanian again for 5-1. A love service hold, punctuated by an ace, followed, and Muguruza found herself up by a set.

In the second set, Tig fell behind 0-2, but the Romanian found a groove on her forehand to pull back level at 2-2. But as the rain came down harder, Muguruza got more determined, and cracked a series of outrageous returns to break Tig at love and reclaim her advantage at 3-2.

Muguruza battled even heavier droplets and a late-match medical time-out where her foot was tended to, but neither of these issues derailed the two-time Grand Slam champion as she collected the final four games of the match to book a second-round meeting with Bernarda Pera. In an all-qualifier battle earlier on Tuesday, Pera defeated Tamara Zidansek, 6-3, 6-2.

Muguruza shrugs off rain in Tig win: Rome Highlights

Earlier on Tuesday, Veronika Kudermetova notched a hard-fought comeback victory with a 4-6, 6-2, 6-3 upset of No.14 seed Elise Mertens in breezy conditions on the Pietrangeli court.

It was a battle between two of the best-performing singles players of the year thus far, who are both currently ranked inside of the Top 8 in the Porsche Race to Shenzhen.

After a back-and-forth final set, it was the Russian, who won her first career title earlier this season on green clay at the Volvo Car Open, who improved to 12-2 on clay so far this year.

Mertens had defeated Kudermetova in straight sets in each of their three previous meetings at Tour-level, including just a handful of weeks ago in Istanbul (where they also teamed up to claim the doubles title).

But the World No.28 at last claimed a victory over Mertens as she fought back from a set down to triumph in two hours and 19 minutes and claim a spot in the second round.

Kudermetova finished the match with an even 40 winners, compared to 31 unforced errors, while Mertens only had 15 winners, which were outpaced by her 24 unforced errors (including nine double faults). Kudermetova made good on five of her 11 break points to clinch the win.

Mertens proved to be the sturdier player in the opening frame, erasing an early 2-0 deficit, then earning a crucial 4-3 lead after forcing errors with heavy forehands. A love hold at 5-4 gave the Belgian the one-set lead.

But the tables turned in the second set as Kudermetova’s aggressive play began to find the court with more regularity, and the Russian earned a critical 4-2 lead by powering a forehand crosscourt winner to break the Mertens serve. Kudermetova earned another break to close out the second set, in which she fired 16 winners to just eight unforced errors.

Kudermetova kept up the momentum in the early stages of the decider, reeling off outrageous passing winners to lead 3-0, but Mertens returned well to edge back to 3-3. However, another winning pass gave Kudermetova the decisive break for 5-3, and the Russian finished off the victory in the next game with a backhand volley.

Having picked up her first-ever victory in Rome, Kudermetova will next face wildcard Caroline Garcia. Former Top 5 player Garcia earned her first-round victory over fellow wildcard Elisabetta Cocciaretto on Tuesday, 7-6(8), 6-2.

Kudermetova stages comeback over Mertens in Rome opener: Highlights