The 23-year-old Brazilian, nicknamed Il Fenomeno and once the greatest striker in the world, was plagued by tendinitis last season and now faces up to five months on the sidelines with a damaged knee tendon.
Inter, who led Serie A early in the season, had lost their way in recent weeks, but a 6-0 home victory against Lecce a fortnight ago and a 1-0 win at Reggina last week has put them back into fourth place. Inter also beat Bologna 2-1 in the Coppa Italia in midweek.
Ivan "Bam Bam" Zamorano, Inter's veteran Chilean striker, is also injured, but Christian Vieri, the club's world record pounds 32m signing, returns from an ankle injury and will partner the under-rated Uruguayan striker Alvaro Recoba, who struck the winner at Reggina and was on the scoresheet against Lecce.
Inter also have problems in midfield. Paulo Sousa and Luigi di Biagio have had their moments, but Francesco Moriero has disappointed down the right. Moreover, Inter's defenders, particularly Laurent Blanc, the veteran Frenchman, have struggled and the goalkeeper, Angelo Peruzzi, has had to get his side out of trouble time and time again.
Eighth-placed Udinese - who won this fixture last term for the first time in 40 years - are not one of the Italian League's bigger clubs, but are usually hard to beat. However, Udinese lost 2-0 to Roma, the leaders, at home last week and were beaten 3-0 at Venezia in the Coppa Italia in midweek.
Udinese lost the Brazilian Marcio Amoroso, Serie A's top scorer last term with 22 goals, to Parma for pounds 24m in the summer, but in Roberto Muzzi, acquired from Cagliari, they have an able replacement. Udinese's goalkeeper Luigi Turci joined his side's lengthy sick list after a bout of influenza on Thursday. Replacement Morgan De Sanctis is on stand-by.
FIXTURES (league positions in brackets): This afternoon: Juventus (3) v Bologna (9). Tonight: Perugia (7) v Lazio (2). Tomorrow afternoon: Bari (10) v Piacenza (14); Internazionale (4) v Udinese (8); Parma (6) v Torino (12); Roma (1) v Lecce (13); Venezia (17) v Reggina (15); Verona (16) v Cagliari. Tomorrow night: Milan (5) v Fiorentina (11).Reuse content