Benjani is an injury doubt for the hosts.
The Zimbabwean striker is still struggling with the hamstring problem which forced him to miss Tuesday night's 1-0 defeat at Ipswich and is unlikely to return.
His absence paved the way for Dave Kitson to start his first match since August at Portman Road following a rib injury.
Kitson looks set to keep his place alongside Luke Varney at the top of the 4-4-2 system caretaker bosses Guy Whittingham and Stuart Gray have used since manager Steve Cotterill's departure to Nottingham Forest late last week.
Goalkeeper Stephen Henderson is still keeping Jamie Ashdown, who started the season as Pompey's first-choice, out of the side.
Doncaster will travel to Pompey with a host of injury concerns.
Goalkeeper Chris Kirkland has ended his two-month loan spell with Rovers after making just one appearance, returning to parent club Wigan after suffering a back spasm.
Ryan Mason, another loanee from Tottenham, missed Doncaster's last-gasp defeat to Blackpool on Tuesday with a stomach bug and is a doubt as he continues to feel unwell.
Midfielder John Oster has strained his neck while defender James O'Connor is struggling with a toe injury. Both are considered doubtful but striker Jon Parkin should return after recovering from flu.
Goalkeeper Gary Woods (shoulder) faces several weeks on the sidelines along with the injured trio of striker Chris Brown (knee), midfielder Martin Woods (hip) and defender Adam Lockwood (knee).