ComfortDelGro, Singapore’s largest taxi operator, has held talks with Go-Jek about a potential partnership that could replace its annulled agreement with Uber.

Uber struck a major deal when it tied up with Comfort last December, but that fell apart last month when the U.S. firm agreed to sell its Southeast Asia business to Grab and exit the region entirely. Go-Jek is already looking to step into the void by expanding its Indonesia-based service into Thailand, Vietnam and the Philippines, but now a source tells TechCrunch that the ambitious startup has held early-stage talks with Comfort that could see it enter Singapore as ride-hailing partner for its 15,000 drivers.

Comfort did not reply to a request for comment. A Go-Jek spokesperson said the company “can’t comment on rumor and speculation.”

Go-Jek is valued at more than $4.5 billion and it has raised over $2 billion from investors that include Google, Tencent, JD.com, Allianz and Meituan Dianping. The company started life as a motorbike taxi-hailing app, but it has since expanded into four-wheeled taxis, services on-demand and payments in Indonesia where it is considered the market leader.

The company has always harbored a desire to expand across Southeast Asia and, after Uber’s exit, it is seizing an opportunity. Moves into Vietnam, Thailand and Philippines — which sources told TechCrunch are underway with local teams already hired — make sense since these are markets where Go-Jek can roll out its flagship bike service and potentially others, but Singapore is trickier since motorbike taxis are outlawed.

Go-Jek opened a Singapore office for business development last year, and it believes that there is demand for its services there. Rather than launching from scratch — which a host of smaller services including Ryde and India’s Jugnoo are planning — it is eying a tie-up with Comfort that would give it access to its fleet.

There may be demand driver-side, too. Comfort told its drivers to delete Uber in the wake of the merger deal with Grab, but many of the fleet are reportedly uneasy about Grab being their only ride-hailing option. That’s an angle that Go-Jek could leverage in its talks with Comfort, which are initially exploratory in nature, we understand.