Richmond defender Luke Trainor will miss Saturday's clash with Adelaide at Adelaide Oval after copping a one-match ban for striking West Coast forward Jack Williams in the stomach (ABC News).

The incident happened in the second quarter of Richmond's 11-point win over West Coast at the MCG. Trainor and Williams were jostling in the goal square when the Richmond defender punched his opponent in the midriff — away from the play, in full view of the umpires and cameras (ABC News).

The AFL's match review officer graded the strike as intentional conduct, medium impact and body contact. That combination drew a one-week suspension. The league has been cracking down on gut punches this season, and Trainor's case fell squarely in that category (ABC News; AFL.com.au).

Richmond coach Adem Yze had hoped the incident would cost Trainor only a fine. After the ban was confirmed, Yze didn't mince words, describing the punch as "stupidity" (NT News; news.com.au).

The timing hurts. Trainor's absence leaves Richmond short of a tall defender against an Adelaide forward line headlined by Riley Thilthorpe — a 200-centimetre key-position target who demands a genuine matchup. Going into Adelaide Oval without one of your key defensive talls is a problem the Tigers did not need (ABC News).

For fans still getting their head around the rules: the match review officer reviews every game each week and can charge players for on-field incidents that the field umpires did not penalise at the time. Conduct is graded on impact (low, medium, high or severe), intent (careless or intentional) and the point of contact. The grades combine to produce a penalty — a fine or a suspension measured in matches.

Trainor accepted the penalty. He sits out Saturday. Richmond travel to Adelaide without him.