* Gutierrez stays at Sauber for 2014
* Russian teenager Sirotkin named as test driver
* Only Marussia and Caterham still have vacancies
By Alan Baldwin
LONDON, Dec 21 (Reuters) - Mexican Esteban Gutierrez will race with Swiss-based Sauber for a second season next year with Russian teenager Sergey Sirotkin signed as test driver, the Formula One team announced on Saturday.
Gutierrez will partner experienced German driver Adrian Sutil, who has moved from Force India to replace Nico Hulkenberg in a direct switch with his compatriot.
Sauber also announced the continuation of their sponsorship agreement with Mexican telephone company Telmex, who have backed the racing careers of both Gutierrez and compatriot Sergio Perez.
Telmex will remain a premium partner with their logo having a significant presence on the team's cars. Formula One had hoped for a Mexican Grand Prix next year but those plans have now been pushed back to 2015.
The driver announcement left only back-markers Caterham and Marussia with race seats remaining for 2014 while Britain's Paul Di Resta is out of a job after losing his place at Force India.
"It was a steep learning curve last season, but by working closely with the team I was able to improve continuously," said Gutierrez, 22, who ended the year as the highest-scoring rookie with six points after a difficult start.
"It will be my fourth year with the team, the second as a racing driver, and I feel comfortable in taking the next step," he added.
"The technical challenges in 2014 will be massive. Therefore it will be even more important to know well the people you are working with. I will do my very best to improve even more and support the team the best way I can."
Sauber principal Monisha Kaltenborn was confident the driver would get better.
"Often the results didn't fully reflect his performances," she said of this year.
Sauber have struggled financially of late, with the long-established team recognising their suppliers were having to wait for payment and Hulkenberg coy about whether he had received all his wages.
Sirotkin, and his Russian backers, had been supposed to ease those financial problems by being groomed for a race seat in 2014 but there has been increasing speculation about the strength of that deal.
The team said they still hoped to bring the 18-year-old into Formula One, with Russia hosting a race for the first time next year in Sochi, but he needed more time.
"Our experience of him is as a very focused, calm and talented driver. Now we will continue to support him, including obtaining his super license. Our goal remains to prepare him for a debut in Formula One," said Kaltenborn.
Sirotkin said his main focus for 2014 would be the World Series by Renault, increasingly seen as a stepping stone for Formula One.
This year's World Series champion Kevin Magnussen of Denmark secured a race seat at McLaren in place of Perez, who has joined Hulkenberg at Force India.
"I will work hard to improve myself and to extract the maximum out of this opportunity. Formula One is very complex, so it is important to get an opportunity like this," said Sirotkin.
Russia will have one driver on the starting grid next season, with GP3 champion Daniil Kvyat joining the Red Bull-owned Toro Rosso team.