Michal Kwiatkowski (Team Sky) was the last man standing at Strade Bianche as the Pole soloed clear in the finale to claim victory in an attritional edition of the Tuscan race.

Greg Van Avermaet (BMC Racing) led Tim Wellens (Lotto Soudal) home 15 seconds later, but the chasers never looked likely to get on terms with Kwiatkowski once he established a lead of half a minute on the approach to the finish in Siena.

"I'm so happy, it's an unexpected victory," Kwiatkowski said. "After the difficult season I had last year, I still had a lot of trust from the team. Now the preparation for this season has already paid off. A second victory at the Strade Bianche, it's just amazing."

Kwiatkowski was prominent when the decisive selection of the race took shape on the long sector of dirt road at Monte Sante Marie, the so-called Cancellara segment, with more than 50 kilometres still to go, and he remained an aggressive presence at the front thereafter.

He showcased his strength by leading Zdenek Stybar (Quick-Step Floors) over the climb of Monteaperti and then performing the bulk of the pace-setting on the Colle Pinzuto, by which point he had only Stybar, Wellens and Van Avermaet for company.

When Kwiatkowski won this race in 2014, he waited until the final haul into the heart of Siena to make his decisive attack, bludgeoning his way clear of Peter Sagan on that occasion. This time around, he seized his opportunity on a rise with a shade under 15 kilometres remaining, sensing that his three erstwhile breakaway companions might struggle to organise a cohesive chase.

"We started to play a game after the Sante Marie section – I actually didn't feel so good there – but I thought the best situation was to do my own thing, that's why I went from so far out and I'm glad it worked out well," he said.

It was, however, a victory of raw strength as much as it was of cunning. The on-form Van Avermaet, in particular, was generous in his chase efforts, but was unable to make any inroads into Kwiatkowski's advantage, which swelled to 30 seconds as he bounded up the 18 per cent gradient on the final dirt road section at Le Tolfe.

Rain fell steadily for much of the second half of the race, and the dirt roads were often treacherous, even if the peloton was spared the carnage of the famous downpour that washed over the Giro d'Italia stage to Montalcino in 2010. Kwiatkowski made light of the conditions, and safely navigated the final gravel descent to hold a lead of half a minute as he began the climb to Siena.

Kwiatkowski betrayed few obvious signs of weakness in the final kilometre, remaining in the saddle for all but the steepest part of the climb, and steadily tapping out a rhythm that saw him maintain his advantage over the chasers.

Despite Van Avermaet's acceleration on the climb, it was Kwiatkowski himself who made the only real dent in his advantage, as he slowed almost to walking pace to negotiate the final, rain-soaked corners as the road dipped towards the dramatic finish line in Siena's Piazza del Campo. He punched the air as he crossed the finish line, and issued a timely reminder of his qualities as the Classics appear on the horizon.

Van Avermaet won the sprint for second place ahead of Wellens, 15 seconds down, while Stybar came home in fourth. Tom Dumoulin (Sunweb), who was to the fore all day, came across in fifth place after leading the Orica-Scott duo of Luke Durbridge and Christopher Juul Jensen in a forlorn pursuit of the winning move.

Sagan abandons

As ever at Strade Bianche, there was no shortage of attackers hoping to forge clear ahead of the early dirt road sectors, but it wasn't until the third segment at Radi that the day's early break gained a foothold. There was a surprising name among the leaders, too, as Thibaut Pinot (FDJ) joined Jose Goncalves (Katusha-Alpecin), Marco Frapporti (Androni), Truls Engen Korsaeth (Astana), Quentin Jaregui (Ag2r La Mondiale) and Simone Andreetta (Bardiani-CSF) in a group that gained a maximum advantage of five minutes over the peloton.

There was plenty of method to Pinot's madness, as he survived to finish the race in an assured 9th place. A lethal combination of wind, crosswinds and large crash on the sixth dirt road sector at Pieve a Salti splintered the peloton into shards, with Vincenzo Nibali (Bahrain-Merida) and Fabio Aru (Astana) among those caught irretrievably behind, while Gianluca Brambilla (Quick-Step) was forced out by a crash.

World champion Peter Sagan battled for a time to stay in contact with the second part of the peloton, but he climbed off with 70 kilometres remaining. His Bora-Hansgrohe team later explained that he had been ill coming into the race, but had hoped he might be able to be competitive nonetheless.

By that time, Lotto Soudal were leading the charge at the front of the 15-man chasing group, with Sean De Bie burying himself in the service of Wellens and Tiesj Benoot, and they reached the section of dirt road dedicated to Fabian Cancellara just 1:30 down on the leaders.

It was on the uphill section of the Monte Sante Marie that the winning move began to take shape, when Wellens accelerated, bringing Stybar, Kwiatkowski, Van Avermaet, Benoot, Dumoulin, Van Avermaet and Durbridge with him. Scott Thwaites, Edvald Boasson Hagen (Dimension Data), Luis Leon Sanchez (Astana) and Matteo Trentin (Quick-Step) later bridged up to them, and that twelve caught the remnants of the early break with 35 kilometres remaining.

From there, the race became something of a slugging match, with the front group continuously splintering and reforming, but Kwiatkowski, Stybar, Van Avermaet and Wellens seemed always to be on the right side of the splits. There was little surprise when they eventually forged clear ahead of the finale, though Dumoulin may feel he paid a price for his whole-hearted efforts in trying to close earlier gaps.

Kwiatkowski proceeded to single himself out as the man to watch with his demonstration of strength on the Colle Pinzuto, but when he accelerated 15 kilometres from home, nobody could take his wheel, and the race was his.

Full Results