Nibali has been linked in recent weeks with a move to a potential new Bahraini-sponsored team in 2017, and speaking to Cyclingnews and Gazzetta dello Sport in Bruges on Friday evening, Guercilena said that he believed this project was now the Sicilian's most likely destination.
"To me it seems quite clear that he has chosen the Bahrain project, from what's being said around. We made our offer and we were told that he has made other choices, so we'll move on other fronts," Guercilena said.
The arrival of Segafredo as co-sponsor at the beginning of this season - another new sponsor, CA Technologies, was announced on Friday evening - seemed to strengthen the likelihood of Nibali signing for Trek, and in January, Guercilena confirmed his team's interest in signing the 2014 Tour de France winner.
In an interview with Gazzetta dello Sport earlier this month, however, Nibali appeared to pour cold water on the prospect of moving to Trek-Segafredo, saying: "I don't know how much interest they really have in me."
Nibali has already stated that he would look to bring a group of riders, as well as trainer Paolo Slongo and soigneur Michele Pallini, with him from Astana to any new team.
"We had a clear deadline and once that time passed, we moved in other directions," Guercilena said on Friday. "It's clear that an athlete of his level was interesting to us, and with Segafredo joining Trek as a sponsor, we could have created something interesting, both in Italy and internationally.
"Trek had already offered him a chance to ride last season when it looked as though Astana might lose their WorldTour licence. We showed our interest in Nibali then, we've shown it again this year. We made our offer with a clear deadline and the response didn't come, so we're moving in other directions."
- 12 riders out of contract in 2016
- Trek Factory Racing first in line to sign Nibali for 2017
- Segafredo to co-sponsor Trek Factory Racing
Trek-Segafredo's interest in Nibali was inspired in no small part by the desire to replace Fabian Cancellara, who retires at the end of 2016, with a star name of similar status. Guercilena said that the team was still looking to bring in a high calibre rider for 2017, and the pursuit of Nibali was proof that the team is not necessarily seeking a like-for-like replacement for Cancellara.
"We're open to different solutions, whether it's Classics riders, Grand Tour riders or both," Guercilena said. "We're fortunate that we already have some strong young riders on our team who have shown they can be leaders. We've got Bauke Mollema who's still only 28 and has margin for improvement in the Grand Tours. So we'll support the riders we have already, and we'll look at who's on the market too."