Kyle Edmund's disappointing season continued with defeat to world number 213 Zhang Zhizhen in the first round of the China Open.
The British number one has won only 12 tour matches in 2019 and has now suffered first-round exits at his last four tournaments, including at the US Open last month.
China's Zhang held on to an early break to take the first set, but Edmund saved a break point in the second before levelling the match.
However, Zhang edged out 24-year-old Edmund in a third set tie-break to win 6-4 3-6 7-6 (5).
There was better news for Britain with Dan Evans and Cameron Norrie progressing to the second round.
Evans beat Zhe Li of China 6-3 6-4 and is edging closer to overtaking Edmund and becoming the top-ranked British men's player.
Norrie's opponent Cristian Garin took a nasty tumble during a first-set tie-break and, after losing it, retired injured.
Norrie will play Andy Murray or Matteo Berrettini in the second round on Wednesday.
Jo-Wilfried Tsonga knocked out third seed Kyle Edmund to reach the quarter-finals of the Grand Prix Hassan II in Marrakech.
The Frenchman, who is working his way back up the rankings after knee surgery last year, edged a close battle 7-6(6) 6-3 against last year's runner-up and will face Lorenzo Sonego in the last eight.
The Italian qualifier won by the same scoreline against Robin Haase while fourth seed Gilles Simon comfortably defeated Guido Andreozzi 6-2 6-2 and Taro Daniel saw off Adrian Menendez-Maceiras in three sets.
At the US Men's Clay Court Championship in Houston, Norwegian Casper Ruud upset fourth seed Reilly Opelka after the world number 95 came from a set down to win 4-6 6-4 6-4, while American Ryan Harrison lost to Henri Laaksonen 6-4 7-5.
Elsewhere, Marcel Granollers-Pujol beat Australian Bernard Tomic 6-1 6-2 in less than an hour and second seed Jeremy Chardy fell to Christian Garin 3-6 7-6 (4) 7-6 (7).
British number one Kyle Edmund has been knocked out of the Australian Open 6-3 6-0 7-5 by Tomas Berdych.
It was a horrible draw for Edmund, seeded 13, against a player who has made at least the quarter-finals here in seven of the last eight years but has dropped down the rankings because of injury.
Edmund arrived in Melbourne with doubts over a knee problem and, although he declared himself happy with the progress he has made, he did not move well and offered little until the third set.
As a result of his defeat, the 24-year-old will drop outside of the world's top 20.
British number one Kyle Edmund has pledged to do "everything he can" to be fit for the Australian Open after picking up a knee injury.
The 23-year-old, who is ranked 14th in the world, has withdrawn from next week's Sydney International, which was set to be his final warm-up event before the year's first grand slam in Melbourne.
"I am disappointed that I won't be able to return to Sydney," Edmund was quoted as saying on the Twitter account of the Sydney International.
"I need to focus on my preparations for the Australian Open and do everything I can to be fit for the first grand slam of the year."
Edmund reached the semi-finals of the Australian Open in 2018, losing to Marin Cilic in straight sets, but suffered a shock defeat to Japan's world number 185 Yasutaka Uchiyama on Wednesday in the Brisbane International.
The Australian Open gets under way on January 14.
Kyle Edmund's 2018 season is over after he withdrew from the Paris Masters with a knee injury.
It has been a breakthrough year for the 23-year-old, having become British number one, won his first ATP Tour title and also reaching the semi-finals of the Australian Open in January.
Edmund, whose record is 36-21 for the year, had still been in the race for a place at the ATP Tour Finals in London next month, but needed a good run in the French capital.
However, scans showed fluid behind the knee and he will now rest in order to be fully fit for the 2019 season.
Russian Karen Khachanov was due to be his second-round opponent prior to his withdrawal.
Kyle Edmund's winning run came to an end with defeat by Fernando Verdasco in the second round of the Erste Bank Open in Vienna.
The British number one arrived in Austria fresh from winning his first ATP Tour title in Antwerp.
Edmund defeated Diego Schwartzman in the first round but Verdasco proved just the stronger in a close encounter, winning 6-4 3-6 6-3.
The Spaniard, who like Edmund has had a fine season, had the better of three breaks to start the match and held on to take the opening set.
Edmund hit back well, breaking serve at the start of the second and levelling the match, but one break proved the difference in the decider and it is Verdasco who moves through to a quarter-final with either John Isner or Gael Monfils.
Edmund heads to Paris for the final Masters tournament of the season, which he would need to win to give himself a chance of qualifying for the ATP Finals in London.
Kyle Edmund's return to court after his maiden ATP Tour title began well as he beat Diego Schwartzman in the Erste Bank Open first round.
The British number one won the European Open in Antwerp on Sunday for his first trophy on the main tour and followed it up with a 6-3 7-6 (3) win against the Argentinian in Vienna.
It was a tough draw for Edmund, who at 14 is ranked only three places above Schwartzman, and there was very little to choose between the two.
The first set was decided by Edmund's key break of serve at 4-3 and that ended up being the only break point of the match.
Both men dominated on serve in the second set until it went to a tiebreak, where Edmund's winning mentality shone through, taking it 7/3 to seal a straight-sets win.
It was his 11th victory from his last 13 matches and sets up a second-round meeting with Spain's Fernando Verdasco.
British number one Kyle Edmund is through to the last 16 of the Shanghai Masters after victory against Andreas Seppi.
The 23-year-old, who reached the China Open semi-finals last week, continued his good form with a 6-3 6-4 success over the experienced Italian to set up a tie against world number 48 Nicolas Jarry of Chile in the next round.
Edmund saved a break point in the third game of the match before exchanging three further breaks of serve to come out on top and take the opening set, using his trademark hard-hitting baseline game to good effect.
Seppi had another break point at the start of the second set but Edmund survived before taking control of the match with a break to go 3-2 ahead.
Edmund maintained his advantage and closed out the match on serve with a forehand winner to reach the last-16 as he chases a first ATP Tour title.
Kyle Edmund fell at the semi-final stage in the China Open as Nikoloz Basilashvili advanced with a hard-fought 7-6 (8/6) 6-4 victory.
Fifth seed Edmund forced Basilashvili into five break points in a first set which took over an hour, but could only make one of them count before it went to the tiebreaker.
It was Edmund who was on the back foot in the second set with Basilashvili forcing five break points and taking three while Edmund could not take advantage of the one opening he created.
It was Basilashvili's first victory over Edmund in three attempts and the Georgian now advances to face top seed Juan Martin del Potro.
The Argentinian should be well-rested given his semi-final was settled by a walkover, with fourth seed Fabio Fognini forced to withdraw due to an ankle injury.
In Tokyo, home favourite Kei Nishikori advanced to Sunday's final in the Japan Open with a 7-6 (7/2) 6-1 win over eighth seed Richard Gasquet.
The third seeded Nishikori will face qualifier Daniil Medvedev after the Russian saw off Canada's Denis Shapovalov 6-3 6-3 to become the first qualifier to reach the final in Tokyo since Magnus Norman in 2002.
British number one Kyle Edmund battled his way through to the China Open semi-finals with a 6-3 7-6 (7/4) victory over Serbia's Dusan Lajovic.
The 23-year-old was made to work hard for his place in the last four against qualifier Lajovic but came through in an hour and 35 minutes.
Edmund did not lose his serve throughout the match, claiming a break in Lajovic's opening service game which was good enough to win the first set.
It was a tougher challenge for the fifth seed in the second as he had to stave off two break points.
Lajovic also refused to have his serve broken, offering just the one break opportunity to Edmund, and forced a tiebreak, which the Brit won to claim his place in the last four.
Edmund will face Georgia's Nikoloz Basilashvili after the Georgian saw off Tunisia's Malek Jaziri - conqueror of second seed Alexander Zverev - 6-2 6-2.