SHANGHAI: Carlos Alcaraz fell toZizou Bergsin straightsetsatthe Shanghai Masters on Monday, interrupting the former world number one`s in-form return to the professional Tour after being sidelined for months by injury.

The 39th-ranked Belgian beat the second-seeded Spanish star 7-5, 7-6(7/4) in the third round to land the tournament`s biggest upset yet, and will play Tommy Paul next.

`Today wasn`t a good match from my side. I didn`t feel good,` Alcaraz told reporters, crediting Bergs for taking chances and serving big.

`In a few important moments I didn`t play my best, and I would say there were a few moments that he was lucky,` the 23-year-old said of their two-hour battle.

Alcaraz said he was `disappointed` by a loss riddled with errors, which came a week after he won the Tokyo Open, adding he would return home and hit practice.`Right now, you know, all the negative thoughts come to my mind and none of the positives, but I think I will take it, you know, the good things,` he said.

His loss also ensures current world number two Alexander Zverev, the reigning French Open and US Open champion, will replace Jannik Sinner as world number one by the year`s end, with the Italian`s season over due to a knee injury.

Zverev, the top seeded player in Shanghai, will face Alexander Bublik in the last 16 on Tuesday.

`DISBELIEF` Alcaraz started with more quality until Bergs broke the Spaniard`s serve to go up 3-2 in the first set.

Alcaraz grabbed back that break in the next game but was uncharacteristically off-target, sending a mess of shots into the net.

He double-faulted to hand Bergs a critical break point in the lithgame, and lost the first set when a volley went short.

Alcaraz, currently ranked third in the world, was visibly frustrated duringthe secondsetashe vented tohis corner following a series of misfired shots that left him with no points in the fourth and eighth games.

He forced a tie-break but could not reach a third set as Bergs closed things out on the first match point.

`It`s a little disbelief and not feeling too much,` Bergs, 27, said after winning.

`You`re just really in the moment, being focused on the points you have to play,` he said.

FRITZ FUMBLES Earlier, Stefanos Tsitsipas came back to beat Taylor Fritz 3-6, 7-5, 6-3 and earn a fourth round meeting with Daniil Medvedev, who brushed aside qualifier Dalibor Svrcina 6-2, 6-3.

A wardrobe malfunction delayed victory for the Greek world number43 when a tennis ball tumbled out of the American`s pocket a second time and forced the men to replay a match point.

A tired-looking Fritz, seeded lith, hung on for a bit longer to save the eighth game but could not stick around beyond that, with Tsitsipas holding serve to win at the fifth time of asking.

`I could have done a few things easier, but I ended up being my biggest enemy,` Tsitsipas told the crowd afterwards.

`I turned things around really well towards the end and became friends with myself and played some incredible tennis,` he said.

Felix Auger-Aliassime, Casper Ruud and Rafael Jodar also went throughtothe last16.

American world number 18 Paul sent off last year`s winner Valentin Vacherot 6-4, 6-2 while Botic van de Zandschulp beat eighth-seeded Arthur Fils 7-5, 6-4.-AFP