The forward joined third-placed Roma on loan in the transfer window seeking regular action to boost his chances of making Italy's World Cup squad after falling out of favour at Bayern Munich.
After making a promising start, Toni's plans were set back by a calf injury in January but he returned to training with his team mates this week and Italian media expect him to feature at some point as Roma bid to pull level with Milan in second place.
Roma's midfield and attack may have been reinforced but coach Claudio Ranieri is likely to be more concerned about the defensive blackouts that have cost his side recently.
The Rome club let a two-goal advantage slip in the closing stages of last week's 2-2 draw at Napoli, days after conceding three goals in six minutes in a 3-2 home loss to Panathinaikos as they crashed out of the Europa League 6-4 on aggregate.
"If we conquer three points against Roma we can really think about winning the championship," Brazil centre back Thiago Silva was quoted as saying by Thursday's La Gazzetta dello Sport.
Milan's Clarence Seedorf has fitness problems too and fellow midfielder Gennaro Gattuso is suspended this weekend.
Inter coach Jose Mourinho will have to watch Sunday's home game against Genoa from the stands as he serves the second part of a three-match touchline ban for a controversial handcuffs gesture made in a draw with Sampdoria two weeks ago.
Juventus, who share fifth place with Napoli after last week's 2-0 defeat at fourth-placed Palermo, visit faltering Fiorentina on Saturday.
