Top seed and 2023 Australian Open semi-finalist Magda Linette was bundled out of the ATX Open in the first round on Tuesday after a three-set loss to Varvara Gracheva.

Gracheva, ranked 88th in the world, needed two hours and 31 minutes to get past Linette 6-3 4-6 6-4 in Austin.

The Pole had led 2-0 in the third set before Gracheva hit back with three breaks in the final frame to run away with a shock victory.

Linette's early exit followed that of second seed Zhang Shuai who withdrew from the tournament on Tuesday due to illness.

Fifth seed Sloane Stephens had no such troubles, progressing into the second round with a 6-3 6-3 victory over Taylor Townsend.

Fourth seed Danielle Collins won 6-7 (7-9) 6-2 6-4 over Magdalena Frech in two hours and 32 minutes, while third seed Anastasia Potapova eased past Elizabeth Mandlik 6-2 6-0.

Top seed Caroline Garcia cruised into the second round at the Monterrey Open in Mexico on Tuesday, winning 6-3 6-4 over Slovenia's Kaja Juvan.

Third seed Donna Vekic survived an early scare to win by virtue of a walkover at 2-6 5-0 against Lesia Tsurenko who retired for the second straight tournament.

Fourth seed Elise Mertens was too strong for Diana Shnaider 6-0 6-4, while seeds Mayar Sherif and Elisabetta Cocciaretto also progressed.

Sixth seed Katerina Siniakova, who made last week's Mexican Open semi-finals, was eliminated after a controversial call on match point in a third-set tie-break, losing to Kamilla Rakhimova 7-6 (8-6) 2-6 7-6 (7-5).

Last week's Mexican Open champion Camila Giorgi was knocked out 6-4 7-5 by Romanian qualifier Elena-Gabriela Ruse.