Slovakia's Peter Sagan won a marathon fourth stage of the Tirreno-Adriatico from Amelia to Chieti, while Christopher Horner took the overall race lead.

The Liquigas rider prevailed on the ascent to a hill-top finish at the end of a gruelling 252km stage that took seven hours 24 minutes to complete.

With no serious breakaway, it was a straight race for home on a steep final climb with gradients approaching 19 per cent.

After Johnny Hoogerland (Vacansoleil) and Vincenzo Nibali (Liquigas) made unsuccessful breaks for home, it was Sagan who overhauled his team-mate and won the stage ahead of Roman Kreuziger (Astana) with Nibali third.

Horner (Radioshack), who finished fifth in the same time as Sagan, took the leader's blue jersey, which he took from Matt Goss (Greenedge).

Kreuziger went second overall, ahead of Cameron Meyer, Sagan and Danilo Di Luca.

"We played a two-rider strategy. It was important to win for Liquigas-Cannondale. I’m sorry that Vincenzo didn’t manage to win. But I saw that Di Luca was coming back up and so I went one last time to make sure we won,” Sagan said.

"I feel good and I’m on good form. I hope it lasts for the classics. Milan-Sanremo is the first classic that could be for me and I want to do well, even if luck plays a big part. It’s my first goal. Tomorrow we’ll try and do the stage for Vincenzo. I’m ready to work for him. We’ll see if we can win.”

The seven-stage Tirreno-Adriatico finishes on Tuesday with a time trial in San Benedetto del Tronto.

Alex Chick / Eurosport