"We need to see if someone comes out the Vuelta, you usually get some stars emerging. We are going to remain calm for now," general manager Luca Guercilena told Cycling Weekly.
"It's clear that the trading has advanced, riders have made their decisions, but you never know what happens on the market and you might find an opportunity."
Three-time Vuelta a España winner Contador starts the three-week Spanish tour, his last race, on Saturday.
Mollema, 30, began the Tour de France this July in a support role for Contador after placing seventh overall in the Giro d'Italia. He won to Puy-en-Velay on stage 15 of the Tour and and finished 17th overall.
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In past editions of the Tour, he placed sixth and seventh overall but has fared better in the Vuelta, placing fourth in 2011.
Alberto Contador at the 2017 Tour de France (Sunada)
(Image credit: Yuzuru Sunada)
"Mollema becoming more and more solid every year and we want to support him. We'd like to find someone for the Giro, maybe not already for 2018, but someone we can work with over time," Guercilena continued.
"We are going to assess the opportunities when they come. We are not going to go crazy because we have to replace Alberto at all costs."
"When you make an investment like that, it takes time and planning before you decide.
"We have good rider in the team already [with Mollema]. Clearly, though, Alberto won't be easy to replace, but since we made investments to grow with young riders a couple years back, we are in a place to work on that."
Trek had thought that the team would begin 2018 with Contador and Mollema, and had budgeted accordingly when looking at signing new riders.
However, after a disappointing Tour de France, 34-year-old Contador decided to end his career already in 2017.
Time passed in the short and precious transfer window before Contador made his retirement announcement on August 7. In that time, some big riders, like Fabio Aru, already inked deals with other teams.
"[Aru is] a classy rider, he showed that in the Tour, but we can't regret how things have gone," Guercilena said.
"Clearly, the market moved on, but let’s see what happens in the Vuelta if something comes up."
Of the big stage racers, only Fabio Aru and Daniel Martin have yet to announce his 2018 plans. It is unclear if Martin, sixth in the Tour, will stay with Quick-Step, move to a team like UAE Team Emirates as rumoured or find another team.
Aru, racing in the Vuelta, reportedly already agreed to a deal with UAE.
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