That's what i would do. I'm not a fan of the line-up Sadomin proposed, which has Molinaro as RB and De Ceglie as LB. It took light years for Molinaro to start playing ok, and combine well with Nedved. I'm pretty sure he'll be completely lost on the right side with Marchionni, and to mark Zarate on top of it. Plus i don't like De Ceglie on LB, especially as a defender.
I'd rather keep Molinaro on the left side, put Mellberg on the right side where he played really wll so far, and only add Ariaudo in the center next to Legro.
It was a bad timing to lose two starters from the defense. We're playing against a team whose power lies completely in the attack. Lazio's attack is like 99% of the team. They scored 29 goals so far, only 2 less than us and only 3 less than league's best attack this season.
With the defense we have atm, we simply must win the midfield and we must repeat the match against Udinese when we didn't let a ball pass through our midfield, which left Quag, Di Natale and Pepe jobless.