The UK's taxi app market has stepped up a gear with the launch of Indian firm Ola's services in London.
The ride-hailing company began operating in Cardiff in 2018 and has since spread to other UK locations.
It has its sights trained on US-based rival Uber, which is appealing against a decision to end its London licence following repeated safety failures.
But one expert sees the sector as a "winner-take-all" market that can only be profitable as a monopoly business.
Ola says it already has three million customers across the UK and hopes to be number one in London within a year.
However, it is not the only challenger to have moved in since Transport for London (TfL) said Uber was "not fit and proper" to be a licence holder.
So what are Ola's chances of knocking out its competitors? And how does it compare with other services?
What is the state of the market?
Ola's services in London began on Monday and its licence will initially run until the end of 2020.
It already offers its services in large parts of the country, including seven big UK towns and cities: Bath, Birmingham, Bristol, Cardiff, Exeter, Liverpool and Reading.
Across the UK, there are now about a dozen app-based ways to book a cab.
Some work with traditional licensed taxi drivers and are merely an alternative to making a phone call. But the majority are hoping to displace Uber by building their own networks of drivers.
Uber is still operating in London after appealing against the decision not to renew its licence.
But however bleak its long-term prospects may seem, it still has the advantage of brand recognition - and it still has more registered drivers in London than any of its rivals.
Uber has 45,000 drivers in the capital, as against 35,000 for its closest rival, Bolt. Ola has recruited 25,000 drivers in London, while another contender, Kapten, has 20,000.
