Lewis Hamilton trails Daniel Ricciardo in Mexican Grand Prix second practice

Hamilton leads Vettel by 66 points in the standings with three races left

Red Bull's Daniel Ricciardo headed Mercedes driver Lewis Hamilton in a closely contested second practice at the Mexican Grand Prix.

Ricciardo was 0.131 seconds quicker than Hamilton, who had a spin early in the session, with Max Verstappen's Red Bull ahead of Sebastian Vettel.

Vettel was only 0.032secs off Hamilton as the Ferrari driver clings to his fading title hopes.

Hamilton needs only to finish fifth on Sunday to clinch a fourth championship.

If Vettel is second in the race, Hamilton needs only ninth to clinch the championship. If the German finishes anywhere else, Hamilton takes the crown regardless.

• Results from Friday's practice sessions

• Relive Friday's action as it happened

• Hamilton wants to win title 'the right way'

• Mexican Grand Prix coverage details

Hamilton shows form after 'big spin'

The 32-year-old Briton had appeared to be struggling, his spin early in the second session following his being nearly 0.5secs slower than Bottas in the first.

But he ended the session 0.3secs quicker than Bottas and with an impressively quick race-simulation run in the second part of the session.

Hamilton and Ricciardo were evenly matched on long-run pace when comparing their equivalent laps - but the Australian stopped his after just four circuits while Hamilton went on to do a huge 27-lap run.

Vettel appeared about half a second slower than the Mercedes and Ferrari but his pace may have been affected by the fact that his session was disrupted by a technical issue, and he said he was not happy with the balance of the car.

However, Red Bull do not have the extra power mode in qualifying trim so will likely have to fight past the Mercedes and Ferraris if they are to compete for the victory.

"The car did not feel great this morning," said Hamilton. "I made some good changes and then had that big spin and destroyed that first set of tyres, but fortunately recovered with not such a bad couple of laps on the ultra-soft and then I did a very long run - 27 laps.

"I think it is going to be close. I was expecting us potentially to be worse off here but it is looking quite good."

Fire extinguisher goes off in Vettel's car

Vettel had an unusual problem halfway through the session when his fire extinguisher went off in the cockpit.

"Another Friday that didn't go 100% right," said Vettel, a reference to a spin and then handling problems he experienced in the US last weekend. "We had a fire extinguisher let go.

"Initially it was just burning but it turned out to be very cold. I had to go back and we changed it and lost some time.

"The car was a bit so-so. Some laps were good others not so but the car in general is quick. We need to work a little bit. It is more about finding the balance and then we should make a good step forward."

Only 0.5secs separated Ricciardo in first place and Bottas in sixth, while the next bunch was also closely matched.

McLaren's Fernando Alonso, who was seventh fastest but has a 20-place grid penalty for using too many engines this season, was just 0.5secs quicker than Renault's Carlos Sainz in 11th.

Force India's Sergio Perez were eighth and 10th, split by Renault's Nico Hulkenberg.

New Zealander Brendon Hartley, continuing with Toro Rosso for the rest of the season after his debut in the US last week, maintained his strong form with 13th, behind Williams' Felipe Massa.

His team-mate Pierre Gasly, back after missing the US Grand Prix for a race in Japan that ended up being cancelled, was 19th after limited running with technical problems.

Haas' Romain Grosjean suffered a spin and subsequent tyre failure and managed only three laps.

Grosjean's team-mate Kevin Magnussen, who was 17th fastest, was taken ill and sent back to his hotel straight after practice. The Dane will be checked over by the medical delegate before final practice on Saturday morning.

Giant figures depicting skulls brought colour to the track before practice started