Rome - Britain's Tour de France runner-up Chris Froome won the fourth stage of the Tirreno-Adriatico on Saturday to close in on the leader's blue jersey.
Poland's Michal Kwiatowski took fourth on the bumpy 173km run from Narni to Prati di Tivo to take charge of the general classification.
He finished 13 seconds behind Froome and now leads the Sky man by four seconds overall.
Italians Mauro Santambrogio and Vincenzo Nibali took second and third on the stage, the latter moving up to third overall at 16 seconds.
In the first mountain stage of the week-long race, the overall contenders came to the fore to shake up the standings.
Former Tour de France winner Alberto Contador twice made a break for home in the final 6km before being joined by Nibali and Santambrogio.
Another former Tour winner Cadel Evans of Australia found the going too tough and fell out of contention while Joaquim Rodriguez struggled on the final climb and lost over 40 seconds.
Nibali attacked with 900m to go but Froome counter-attacked with just 700m left, leaving his main rivals in his wake and putting time into all of them.
Contador lost 15sec and now sits fourth overall at 30 seconds while Rodriguez is 10th and over a minute back.
Froome's strong showing bodes well for his Tour chances later this year when he will be the Sky team leader as reigning champion Bradley Wiggins concentrates his attentions on May's Tour of Italy.
The last two winners of the Tirreno have gone on to shine in the Tour, with Evans winning it in 2011 and Nibali taking third spot, behind Wiggins and Froome, last year.
Froome was greatly helped by a strong showing from his Sky team-mates, who controlled the pace on the final climb.
"I had faith in my teammates, when they work like that it makes my job easy," said the winner.
Results from the fourth stage of the Tirreno-Adriatico, a 173km run from Narni to Prati di Tivo on Saturday:
1. Christopher Froome (GBR) Sky 4hr 41min 31sec
2. Mauro Santambrogio (ITA) Vini Fantini at 6sec
3. Vincenzo Nibali (ITA) Astana 11
4. Michal Kwiatkowski (POL) Omega Pharma 13
5. Christopher Horner (USA) RadioShack 15
6. Alberto Contador (ESP) Team Saxo same time
7. Rigoberto Uran Uran (COL) Sky 20
8. Wouter Poels (NED) Vacansoleil 43
9. Joaquim Rodriguez (ESP) Katusha s.t.
10. Roman Kreuziger (CZE) Team Saxo 58
1. Michal Kwiatkowski (POL) Omega Pharma 16:04:59
2. Christopher Froome (GBR) Sky 4
3. Vincenzo Nibali (ItA) Astana 16
4. Alberto Contador (ESP) Team Saxo 30
5. Rigoberto Uran Uran (COL) Sky 33
6. Christopher Horner (USA) RadioShack 40
7. Mauro Santambrogio (ITA) Vini Fantini s.t.
8. Jonathan Castroviejo (ESP) Movistar 1:04
9. Roman Kreuziger (CZE) Team Saxo 1:16
10. Joaquim Rodriguez (ESP) Katusha s.t.