Fourth-placed Samp play Genoa in the city derby on Saturday and will again pin their hopes on mercurial forward Cassano, constantly overlooked by Italy coach Marcello Lippi despite fan protests.
Totti, who bagged a hat-trick on his return from a two-month injury layoff in last weekend's 3-1 win over Bari, is catching Lippi's eye even though he is retired from international soccer.
The 33-year-old Roma captain has consistently hinted in recent months that he would consider going to June's World Cup in South Africa if asked by Lippi, who was careful with his words this week.
"I was really happy for Totti's hat-trick because once again he has been able to react well after an injury and come back superbly," he told Reuters.
Mid-table Roma, under pressure from banks to find a solution to their debt problems after two failed takeovers in two years, will also have Daniele De Rossi available against Atalanta but he will be forced to wear a mask after breaking a cheekbone.
De Rossi will also be with Italy in South Africa but Cassano has already planned his wedding for June, such is his certainty that he has failed to persuade Lippi he is no longer the wild child of old.
Leaders Inter Milan, comfortably beaten 2-0 by Barcelona in the Champions League on Tuesday, have problems at right back for Sunday's home game against Fiorentina with Maicon suspended and Davide Santon injured.
Captain Javier Zanetti is likely to drop back from midfield.
Second-placed Juventus, who host Inter in two weeks, will hope their fans behave away to Cagliari on Sunday after being fined for recent chants against Inter's black striker Mario Balotelli.
Reports said the songs were heard again in Wednesday's Champions League defeat at Bordeaux.
