Westhoff was charged with striking Essendon's Cale Hooker during the three-quarter time break at Etihad Stadium on Sunday.
It was adjudged by the Match Review Panel as being intentional, of low impact and high contact, constituting an offence worth 225 points under the AFL's review system.
That total was reduced to 168.75 points when Westhoff's good record was taken into account, constituting a one-match ban.
An unsuccessful challenge would rule the half-forward out of Saturday's game against Hawthorn at AAMI Stadium
Essendon's David Myers was cleared of striking Port's Robbie Gray during the match.
portadelaidefc.com.au will provide ongoing coverage of Westhoff's challenge from 4:30pm on Tuesday.
