Agnieszka Radwanska needed three sets to get past Roberta Vinci and reach the semi-finals of the Qatar Open on Thursday.
Radwanska, seeded third, defeated the Italian 3-6 6-2 6-3 in one hour, 52 minutes at the Khalifa International Tennis and Squash Complex in Doha.
Vinci looked set to cruise into the last four of the outdoor hard court event during a nerveless display of serving in the first set, the ninth seed not facing a single break point, while breaking her Polish opponent twice.
But that composure was nowhere to be seen after the 33-year-old was broken in the first game of the second set, giving up her serve five more times as world number three Radwanska roared back to advance.
She must overcome Carla Suarez Navarro to reach the decider after the Spaniard defeated qualifier Elena Vesnina 6-3 7-6 (7-3).
Both players struggled to hold serve in their last-eight match, Vesnina broken five times across the two sets and winning just one point on serve in the tie-break, as Suarez Navarro secured a victory that will see her return to the top 10 in the world rankings.
Jelena Ostapenko followed up her shock victory over Petra Kvitova by defeating Zheng Saisai in straight sets, the Latvian winning 6-4 6-3 to book a meeting with Andrea Petkovic in the semi-finals, which will be her first appearance in the last four of a WTA Premier event.
German Petkovic upset fourth seed Garbine Muguruza in three sets, giving up her serve just once and breaking the Spaniard five times to win 6-1 5-7 6-2.