Despite having won stage two on Sunday, Sagan didn’t appear to want today’s stage to come down to a sprint as he attacked on the final climb, a move that was quickly closed down by Michael Matthews and Team Sunweb.
A nervy finale followed with no one seeming to be willing to take full control of the front of the bunch, which gave the opportunity for Arthur Vichot (Groupama-FDJ) to attack under the flamme rouge.
Daniel Oss (Bora-Hansgrohe) tried to bring the Frenchman back to set up Sagan’s sprint, but everyone was surprised as Colbrelli went early on the left-hand side of the road.
Michael Albasini (Mitchelton-Scott) immediately jumped on Colbrelli’s wheel with Sagan close behind, while Gaviria stuck to his guns and sprinted on the opposite side of the road.
Vichot was soon caught but Sagan, who appeared to be carrying the most speed, made the mistake of jumping across to Gavria’s wheel rather than following Colbrelli, who was able to hold off his two bigger-name rivals to take a fine stage win.
Meanwhile Stefan Küng (BMC Racing) finished safely in the main bunch to maintain the race lead.
How it happened
The third stage of the 2018 Tour de Suisse saw a fairly sedate start as Fabien Grellier (Direct Energie), Calvin Watson (Aqua Blue Sort) and Filippo Zaccanti (Nippo-Vini Fantini) attacked from the gun and the peloton immediately sat up with BMC Racing and race leader Stefan Küng content to let three unthreatening riders go clear.
Zaccanti had been in the break on stage two and, with five small classified climbs in the second half of the stage, was on the hunt for mountains points.
Those three riders quickly opened a lead of around five minutes, which stayed fairly steady for much of the day until BMC Racing started to reel the group in as they approached the finishing circuit around the town of Gansingen.
With 80km to go the break’s lead was brought down to a slightly more manageable three minutes as Grellier took the prizes at the top of the climbs and the gap settled down again and remained largely unchanged at around the three minute mark.
However the input of Bora-Hansgrohe, with Maciej Bodnar working hard for team leader Peter Sagan, saw the gap steadily come down and by the time the break hit the third of the five third-category climbs with 37km to go their lead was down to just 1-20.
That smaller gap encouraged Chris Juul Jensen (Mitchelton-Scott) to attack off the front of the peloton, the Danish rider crossing the top of the climb 44 seconds behind Grellier – who beat Zaccanti to maximum points – with the peloton a further 20 seconds in arrears.
Grellier and Zaccanti’s battle for mountain points had seen Watson dropped from the break, with the Australian picked up by Juul Jensen who had managed to open his lead over the peloton up to a minute.
The riders crossed the finish line for the penultimate time with slightly under 30km to go, with Grellier and Zaccanti holding a lead of 26 seconds over Juul Jensen and Watson, with the peloton – led by BMC Racing – now 1-34 off the lead duo.
The road started to ramp upwards immediately after the line, which saw Watson drop off Juul Jensen’s wheel, who quickly made his way across to Grellier and Zaccanti with 26km remaining as the riders toiled through heavy rain, while the gap to the bunch was down to just a minute as Dimension Data, Mitchelton-Scott, and Ag2r La Mondiale all challenged BMC Racing at the front.
BMC Racing appeared to not only be trying to protect the lead of Küng, but also to set Greg Van Avermaet up for the win, as they continued to chase hard to bring the gap down to 40 seconds on the approach to the final climb of the day.
The chase hotted up further over the following kilometres and the break was caught with nine kilometres to go and it was up to Quick-Step Floors to lead on to the climb a kilometre later.
As soon as the road ramped up the attack came from Katusha-Alpecin, with José Gonçalves launching the first move but being unable to open a gap and soon being shut down by Omar Fraile (Astana).
The next attack came from a slightly bigger name as Peter Sagan (Bora-Hansgrohe) sparked a big reaction behind with Michael Matthews (Team Sunweb) the first rider to jump onto his wheel before Sunweb took control at the front.
A slight rise in the last kilometre saw Arthur Vichot (Groupama-FDJ) attack, but Bora-Hansgrohe had regrouped on the front with Daniel Oss trying to chase down the Frenchman.
However Oss wasn’t making enough in-roads for Sonny Colbrelli (Bahrain-Merida) launching an early sprint on the left-hand side of the road that caught out some of the other sprinters.
As the Italian made his move Fernando Gaviria (Quick-Step Floors) and Sagan both hesitated, and Colbrelli had the power to hold off his bigger name rivals to win the stage by a very narrow margin over Gaviria.
Meanwhile Stefan Küng crossed the line in the front group to maintain the race lead.
Tour de Suisse 2018, stage three: Oberstammheim to Gansingen, 182km
1. Sonny Colbrelli (Ita) Bahrain-Merida, in 4-39-51
2. Fernando Gaviria (Col) Quick-Step Floors
3. Peter Sagan (Svk) Bora-Hansgrohe
4. Michael Albasini (Sui) Mitchelton-Scott
5. Magnus Cort (Den) Astana
6. Michael Matthews (Aus) Team Sunweb
7. Enrico Battaglin (Ita) LottoNL-Jumbo
8. Jasper Stuyven (Bel) Trek-Segafredo
9. Diego Ulissi (Ita) UAE Team Emirates
10. Sep Vanmarcke (Bel) EF Education First-Drapac, all at same time
General classification after stage three
1. Stefan Küng (Sui) BMC Racing, in 8-50-15
2. Greg Van Avermaet (Bel) BMC Racing, at 3 secs
3. Richie Porte (Aus) BMC Racing
4. Tejay van Garderen (USA) BMC Racing, all at same time
5. Peter Sagan (Svk) Bora-Hansgrohe, at 20 secs 00:00:20
6. Michael Matthews (Aus) Team Sunweb, at 23 secs
7. Wilco Kelderman (Ned) Team Sunweb
8. Sam Oomen (Ned) Team Sunweb, all at same time
9. Gregor Mühlberger (Aut) Bora-Hansgrohe, at 30 secs
10. Enric Mas (Esp) Quick-Step Floors, at same time