With Sichuan's offense bogged down, Dongguan retook the lead and delivered the final blow with efficient offensive late in the fourth to make it 78-71.
Koeman had made no secret that he wanted the duo and the failure to sign Garcia leaves Barca looking especially lightweight in central defense, where they only have Gerard Pique and Clement Lenglet, with Ronald Araujo to provide cover.
Earlier, Schwartzman knocked out third seed Dominic Thiem in a thrilling marathon battle which lasted over five hours, winning 7-6 (7-1), 5-7, 6-7 (8-6), 7-6 (7-5), 6-2.
"I don't know what happened actually, I felt like I was playing perfectly, I was so focused the whole match, even I am surprised that I can do that," said the 54th-ranked Swiatek, who fired 30 winners and won 81 percent of her first-serve to wrap up the victory.
Li felt a bit uncomfortable about Shandong's double team early in the match, but soon get used to that, making two baskets and feeding Chen's two layups, to help Inner Mongolia race ahead 19-15 in the first quarter.
"We did well on defense," said Inner Mongolia coach Zheng Wei, also assistant coach of China's national team, adding the team still needs to build its chemistry through more game time.
Barcelona talisman Lionel Messi has been unfairly maligned by some for a perceived inability to reproduce his club form for Argentina. But the 33-year-old's record for his country stands tall against the greats of any era. Messi is his country's all-time leading scorer with 70 goals and 45 assists from 138 appearances.
1: Barca still has work to do
On the men's side, 12-time Roland Garros winner Rafael Nadal continued his run after dropping only four games to complete a 6-1, 6-1, 6-2 win over American youngster Sebastian Korda, son of 1998 Australian Open winner Petr Korda. Enditem
Villarreal travels after an easy 3-1 win at home to Alaves and with strikers Paco Alcacer and Gerard Moreno both in excellent form after netting six goals between them in Villarreal's first four games of the season.
Luo Xinyu bagged 18 points for Jiangsu, who also got 14 points apiece from Xu Chenyan and Jiang Jiayin.