Beer Sheva scored the only goal after just four minutes of play with a penalty from Portuguese midfielder Josue, after Plzen's goalkeeper Ales Hruska fouled Colombian striker Jhonatan Agudelo.
More setbacks could well affect the entire season and increase the pressure on coach Lucien Favre at an early stage.
The hosts dominated early as Jorge Recalde scored either side of a Carlos Sanchez penalty at the Manuel Ferreira stadium in Paraguayan capital Asuncion.
"Of course, I will make sure I don't make the same mistake twice," he added.
Stage two containing eight groups will be held from October 26 to 29. Stage Three with two groups is scheduled to play on October 30 and the final is on October 30. Enditem
Real Sociedad ruined Elche's return to the top flight as they won 3-0 in Elche's Martin Valero stadium, with all the goals coming in the second half.
Willy Caballero replaced Kepa in the Chelsea goal, but had picked the ball out of his net three times by the 27th minute as Callum Robinson scored twice and Kyle Bartley made it 3-0.
"I am really happy about my first round. I was facing another great champion today. The transition to clay and the cold conditions worked out pretty well," said Thiem.
The top 16 world-ranked male and top 16 world-ranked female players will fight for glory at the ITTF Finals, with a cap of four players for each association.
Tourists can participate in a photo contest, enjoy traditional singing and dancing programs as well as discover Mongolian cuisine during the festival.
Fiorentina's Federico Chiesa celebrates his goal during a Serie A soccer match between FC Inter and Fiorentina in Milan, Italy, Sept. 26, 2020. (Photo by Alberto Lingria/Xinhua)