Juan Pablo Carrizo will not be able to join Lazio until 2008 because he has been unable to secure a work permit.
The Italian outfit had completed a deal for the River Plate goalkeeper, but the move has been held up because Lazio have been unable to obtain an EU work permit for the Argentinian international.
Carrizo has therefore returned to River Plate on loan until 2008 and Lazio have secured the stop-gap signature of Fernando Muslera from Uruguayan side Nacional to solve their goalkeeping crisis.
Lazio have been searching for a new shot-stopper following the retirement of Angelo Peruzzi at the end of last season and they have been forced to field 43-year-old Marco Ballotta so far this season.
Ballotta has performed well, but Lazio have welcomed the arrival of Muslera as they bid to secure a long-term goalkeeper.
"Muslera is a lad with personality, a great technique and a strong temperament," said Lazio president Claudio Lotito.
"For now he is here then Carrizo will also arrive. We want to settle the future of this position for the next 10 years."
Meanwhile, River Plate have welcomed the temporary return of Carrizo.
"This is good news for Argentinian football," River Plate secretary Hector Cavallero told Radio La Red.
"Lazio will pay us the transfer fee but, as they can't use Carrizo, they will loan him to River.
"The only thing that will change is the way in which the transfer will be paid. It will now be in several quotes and not in cash."