Koeman changed the style Barca used under Quique Setien, adapting a 4-2-3-1, with Antoine Griezmann leading the line, Frenkie de Jong and Sergio Busquets in the midfield holding roles and Messi, Philippe Coutinho and Ansu Fati in an attacking line of three.
"We are a team under construction and we didn't have time to try more solutions in the pre-season, so let's try to find them in these first few games," he added.
Earlier on Sunday, Wissam Ben Yedder struck in each half as nine-man Monaco held on to overcome Strasbourg 3-2 at home. Right-back Ruben Aguilar added another for Niko Kovac's side in stoppage time of the first half.
That performance has put Athletic coach Gaizka Garitano under pressure and both he and Machin need wins to assure they are still in their jobs after the international break.
Tokyo 2020 said that it is reviewing a number of COVID-19 countermeasures for the torch relay, consulting with experts and the health authority in the aim of ensuring a safe and secure event.
The 16-team CSL was split into two groups respectively in Dalian and Suzhou. Both groups will play 14 rounds in the first phase, which is to end next Monday.
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.
Shanghai led by as many as 35 points in the final period.
Fernando opened the scoring for Guoan in the 17th minute, as he sent Zhang Yuning's pinpoint through ball into the top-left corner.
Following is the Mexico squad:
Baum faces a big challenge at Schalke, who are on a run of 18 winless games since January 2020. The new Bundesliga season began with a heavy 8-0 defeat to Bayern Munich, followed by an uninspiring 3-1 loss to Werder Bremen, leaving Schalke with zero points and in last place in the table.