Ilnur Zakarin in pole position at rainy Imola

Riding his debut Giro after a surprise overall victory in the Tour of Romandie earlier this month, 25-year-old Zakarin underlined his promise with a gutsy break 20km from the finish of the undulating 153km stage in Emilia-Romagna in northern Italy.

Former Russian time trial champion Zakarin, of the Katusha team, broke clear on the third of three ascents of the punchy Tre Monti climb on a 15km finishing circuit that included part of the famous Imola motor-racing track.

Zakarin held on to take a memorable victory by 53 seconds over the chasing group, which was led over the line by Colombia's Carlos Betancur (Ag2R-La Mondiale).

The overall standings remain unchanged despite an attack by race leader Alberto Contador on the fourth and final ascent of the circuit climb inside the last 10km of the stage.

Tinkoff-Saxo's Contador was reeled in and finished safely in the main pack 58 seconds down on Zakarin to retain his three-second lead over Italy's Fabio Aru (Astana).

Australia’s Richie Porte (Team Sky) had a quiet day in the saddle after the setback of being docked two minutes by the race organisers for his part in the wheel-change imbroglio that animated the closing moments of Tuesday’s stage 10.

Porte is currently 12th place on GC over three minutes down on Contador thanks to a combination of that penalty and the time lost for the initial puncture.

Colombia’s Rigoberto Uran (Etixx-QuickStep) crashed on the slippery road on the penultimate lap but managed to fight back into contention to finish in the group of main favourites. Uran stays sixth on GC at 2:10.

TEN-MAN BREAK: After 25km of aggressive racing following the start in Forli, a break of ten riders managed to extricate itself from the rain-soaked peloton on the first of two Cat.3 climbs.

The break contained some familiar faces, with Zakarin joined by a cluster of riders who had already featured in moves of varying success earlier in the race, notably Colmbia’s Betancur, Spain's stage 8 winner Benat Intxausti (Movistar), flame-haired Dutchman Steven Kruijswijk (LottoNL-Jumbo), 2012 overall winner Ryder Hesjedal (Cannondale-Garmin) of Canada and veteran Italian Franco Pellizotti (Androni Sidermec).

Italians Matteo Montaguti (Ag2R-La Mondiale) and Diego Rosa (Astana), Poland’s Marek Rutkiewicz (CCC Sprandi Polkowice) and Spaniard Ruben Fernandez (Movistar) completed the roster as the leaders opened up a maximum gap of around four minutes on the pack.

Perhaps eager to avoid a repeat of Tuesday’s stage – where a rudderless chase in the peloton led to the break staying clear on a flat stage tailor-made for the sprinters – the pack monitored the gap closely, with the BMC team of Belgium’s Philippe Gilbert doing the lion’s share.

TENSE FINALE: With Intxausti picking up enough points to move back into the blue mountains jersey, the advantage of the break dropped to as low as 1:20 as the break embarked on the second of three ascents of Tre Monti with 40km remaining.

But heavy rain led to inevitable slower speeds in the pack as the Tinkoff-Saxo team of Contador looked to keep their man out of trouble.

BMC upped the chase, leading to Austria’s Stefan Kung momentarily pulling clear of the pack on a descent. Kung had almost caught the remnants of the break by the time he was himself reabsorbed back into the streamlined peloton, by now down to around 50 riders.

The Orica-GreenEdge team of Michael Matthews also committed themselves to the chase – but it proved too much, too late after Zakarin caught his fellow escapees napping with his unexpected attack 20km from the finish.

Soon holding a minute’s advantage over the disorganised chasing group, Zakarin had only to negotiate the final slippery descent to the finish to secure the biggest win of his career.

CONTADOR’S DIG: Back with the peloton, the race leader tested his legs near the top of the final ascent of Tre Monti to open a little gap over his GC rivals.

The Spaniard was reeled in shortly after the summit before Gilbert launched a last-ditch effort to bridge the gap to the escapees.

Contador’s move even baffled his team-mates, with Australia’s Mick Rogers admitting, "I don’t know what that was about, but you know Alberto – when he feels good, he attacks, and that’s why he’s such a great rider.”

The race continues on Thursday with a largely flat 190km stage 12 from Imola to Vicenzo where it may be a case of third-time lucky for the sprinters after back-to-back days being caught out by the likes of Zakarin and previous winner, Nicola Boem of Italy, the current red jersey from Bardiani-CSF.

But a series of small climbs in the final third of the race - plus an uphill drag to the finish - could provoke a frantic dash to make the day's decisive break.