* Liquigas win team time trial on fourth stage
* Nibali holds 13-second lead over team mate Basso
Vincenzo Nibali, who had not been due to be compete in this year's Giro d'Italia, snatched the leader's pink jersey on Wednesday after his Liquigas outfit won the team time trial on the fourth stage.
Nibali was a late Liquigas replacement for one of the favourites, Franco Pellizotti, who was withdrawn before the start of the race because of a doping probe after problems emerged with his blood data.
"I wasn't even meant to take part in this Giro but just you now try taking this pink jersey off me," Nibali growled at a news conference.
"The Giro wasn't in my plans but I definitely won't let the pink jersey go without spending every last drop of energy."
Team mate and Italian compatriot Ivan Basso, the 2006 Giro winner, is 13 seconds behind in second in the overall standings.
Previous race leader Alexandre Vinokourov of Astana slipped back to sixth following Liquigas's lightening time of 36 minutes 37 seconds on the 33-km route from Savigliano to Cuneo in north western Italy.
Team Sky, whose top rider Bradley Wiggins led after stage one, were second in the time trial but 13 seconds adrift.
The previous three stages took part in Netherlands where high winds contributed to a raft of crashes with Wiggins and his title hopes poleaxed twice.
Tuesday was a rest day as the riders returned to Italy for the rest of three-week race.
Thursday's fifth stage is a 162-km route from Novara to Novi Ligure.
The Giro ends in Verona on May 30.
(Writing by Mark Meadows, editing by Miles Evans. To query or comment on this story email firstname.lastname@example.org)