With three days to go, Welshman Geraint Thomas kept the pink leader’s jersey.
The 37-year-old Ineos Grenadiers rider arrived at the line almost two minutes behind Zana together with Slovenia’s Primož Roglič, who is second in the general classification.
Thomas celebrated his 37th birthday by extending his lead at the Giro on another day of gruelling success for Australian team Jayco AlUla at the grand tour.
On his home roads, however, it was Zana, 24, who powered to victory on the mountainous 18th stage, winning a sprint finish with Thibaut Pinot atop the Val di Zoldo in the Dolomites on Thursday.
But it was also a statement day for Wales’ 2018 Tour de France winner Thomas, who strengthened his grip on the leader’s pink jersey by improving his overnight GC lead from 18 to 29 seconds.
There was also a change in his nearest pursuer, with Roglič (Jumbo-Visma) leap-frogging Portugal’s Joao Almeida (UAE Team Emirates) into second despite the heroic efforts of Almeida’s Australian lieutenant in the mountains, Jay Vine.
Zana’s win on a day for the climbers was a second triumph for Jayco after Australian Michael Matthews, who had also finished on the podium on Wednesday, annexed the third stage in the opening week.
The team’s rising Irish star Eddie Dunbar also moved up to fourth overall with another impressive top-10 ride, adding to the outfit’s celebrations.
“I can’t believe it. I have to thank the team because they gave me this opportunity,” Zana, who’d also had a podium finish on the eighth stage, said.
“In the finale I played my cards right, it was an opportunity that comes around a few times in life and I took it. To win with the tricolour jersey is special.”
Pinot and Zana were part of a six-man breakaway on the 161km route who built up a four-and-a-half minute lead with 10km left but the pair ended up dropping their fellow escapees in the brutal finale.
Behind, as the GC contenders sparred, Thomas looked strong as he held firm amid a Roglič attack which suggested the Slovenian still has plenty to give.
Almeida lost his second spot overall but the damage could have been much worse if not for the tremendous assistance he received when suffering on the slopes from UAE Team Emirates’ teammate Vine.
The Australian had caused a stir earlier in the race with a few comments which had been interpreted as him not caring about the race’s final week, but his selfless display in support of Almeida has kept the Portuguese in the hunt in third place, still only 39 seconds behind Thomas.
“To gain time on Almeida and not get dropped by Primož is a good day,” Ineos Grenadiers star Thomas, who’s seeking to become the race’s oldest winner, said.
“It’s nice (to gain time on Almeida) but Primož had a bad day the other day, Almeida today. I’ve just got to keep being consistent. Just take it day by day, climb by climb.”
But Thursday’s stage was just the warm-up act for Friday’s monumental 183km ride from Longarone to Tre Cime Di Lavaredo, featuring three category one ascents, with a total altitude gain of 5400m.
AAP with Agencies