Former England international Barton, 38, denies assaulting Stendel, causing him actual bodily harm after a game between the Tykes and Fleetwood at Oakwell in April 2019.
The ex-Manchester City, Newcastle and Burnley midfielder was managing Fleetwood at the time of the alleged incident.
Barton was charged following an alleged incident in the tunnel after the League One match.
Wearing a dark suit, blue shirt and navy tie, he sat in the dock at Sheffield Crown Court on Monday as a jury was selected for the trial, which is expected to be opened later.
Twelve jurors were selected after a panel was asked a series of questions including “have you heard of Joey Barton?” and “do you have any opinions about Joey Barton?”
The potential jurors were also asked whether they were at the match or watched it on TV and also whether they were Barnsley or Fleetwood supporters.
Judge Jeremy Richardson QC told the jury of six men and six women that the case will be opened by prosecutor Ian Goldsack on Monday afternoon.
It is thanks to our loyal readers that we can continue to provide the trusted news, analysis and insight that matters to you.
For unlimited access to our unrivalled local reporting, you can take out a subscription HERE and help support the work of our dedicated team of reporters.