ATX Open Austin Round-up Day Four | Iva Jovic suffers surprising defeat as only one seed remains in Texas

The ATX Open Austin field has been blown wide open. First the top seed Jessica Pegula withdraws after winning the title in Dubai and now the teenage sensation Iva Jovic is dumped out to the hands of Ajla Tomljanovic, with the world number 74 winning 4-6, 6-4, 6-4.

A lot of the attention at the start of the season has been firmly centred around Jovic and her marvellous runs she produced Down Under. First was reaching the semi-final of the ASB Classic before a surprising final defeat in the Hobart International to Elisabetta Cocciaretto showed just how far she has come. Next was a fantastic run in the Australian Open where she made it all the way to the quarterfinals before proving to be no match for world number one Aryna Sabalenka.

She took a break before coming back for the Dubai Duty Free Tennis Championships, losing out to eventual champion Pegula in the last-16 before making the trip to Texas as the number one seed, ready to challenge for another WTA title and get herself in the best condition ready for the Sunshine Swing.

The 18-year-old will geta bit of rest beforehand as she ends up tumbling out of the tournament to the hands of Tomljanovic. The experienced Aussie would prove to be a tricky task, and that was shown early on when Jovic had to defend break opportunities. She managed this before nicking a break right at the end of the set to put her one to the good.

However, Tomljanovic came charging back. Her chance was finally taken to go 3-2 up in the second set and it would stay on serve as she forced a deciding set. She began this in fine form, accelerating away with a break to love. Jovic got that break back to make it 4-4 but was immediately behind again. On her third match point, Tomljanovic sent the second seed out and was delighted with the victory when she spoke after the match.

"It was really important to not let her get away with the scoreline in the second -- just to stay close, keep my serve, and try to see for the looks on her serve to break," Tomljanovic stated. "It was a really high-level match, and she pushed me to play my best today. I knew that would be required today, and you never know on the day if you'll be able to come up with the goods or not, so I'm really thrilled to have had a great match."

There will be one Australian tennis player in the semifinal stage as Kimberly Birrell defeated Caroline Dolehide 6-4, 6-2. Birrell kicked off the match with a break but just a few games later it was back on serve. Dolehide failed to take a brace of opportunities to sneak ahead, and it would prove to be pivotal. After the American held to make it 4-3, Birrell won the final three games to move out in a commanding lead.

It would get even more ominous for the home crowd when they saw the qualifier go 4-0 down. Birrell was in cruise control and avoided a couple of possible slip ups in the final game to take her third match point and march on.

The other two last-16 matchups saw two straight set wins with Peyton Stearns the only seed left in the competition after a convincing 6-0, 6-2 triumph over Kaja Juvan. The first set was just 24 minutes long as Stearns raced in front, dropping just four points on serve before sealing her lead in emphatic fashion.

The second set was relatively straightforward at first with Juvan finally settled on her serve but unable to do any damage on her opponent. Then Stearns broke the serve to move 4-2 ahead and it was now or never for the Slovenian. At this point she had only taken seven points from her opponent's serve. In the next game she got four. Unfortunately, those points won did not include the two break chances created and Stearns fought on, showing Juvan how it is done by breaking the serve herself to seal a solid win.

There was more American delight for Ashlyn Krueger who proved to have the goods to take down Anastasia Zakharova in a tight 7-5, 6-3 victory.

It was the Russian who stormed ahead in the early stages, taking a break lead that would last the majority of the set. However, she was not able to hold onto it and was eventually blown away by Krueger who won four games in a row while saving two set points to move out in front.

Again, Zakharova stole a match on her opponent, but this time Kruger was much quicker to fight back. She the avoided a break point from Zakharova before taking one herself to go 5-3 ahead. She had no problem serving it out to seal a very solid victory.