On a sunny afternoon at the Autodromo Hermanos Rodriguez, the triple Formula One world champion secured his 59th career pole and 10th of the season with a best time of one minute 18.704 seconds.
"I turned up to do the job and I'm going to try to do the same thing I did last week. So far this weekend’s gone well and I'm looking forward to the race. The car feels great," said the Briton, who won in Texas last weekend.
Rosberg, last year's winner from pole in Mexico, has a 26-point lead with three races remaining and will take the title on Sunday if he wins and Hamilton fails to finish in the top nine.
The German had struggled for performance in practice and the early phases of qualifying and was in danger of qualifying fourth before banging in a 1:18.958 in the dying seconds to rescue the situation.
"Lewis's lap was brilliant, not so much mine but I put it together when it counted in the end," a relieved Rosberg told reporters.
"I just took a bit longer this weekend to find a way, just generally with tyre temperatures it being on the cold side all weekend...but we got there in the end so that’s OK."
Rosberg had been only sixth fastest in phase one and fifth in the second.
Hamilton, who said he was delighted to see a Mercedes front row sweep even if the body language indicated disappointment at Rosberg's late escape, said the last session had been his worst of the weekend.
"But I know going into tomorrow we’ve got the right strategy and I think the car is in a good place for the long runs," he added.
RED BULL SECOND ROW
Red Bull's Dutch teenager Max Verstappen qualified in third place with Australian team mate Daniel Ricciardo fourth.
"I had a good feeling with the car all weekend, I was getting better and better but it was a shame in Q3 (phase three) I couldn't get the lap together. We have a different strategy for tomorrow," said Verstappen.
The 19-year-old will start on super-soft tyres, which are faster but also wear more quickly, while the Mercedes drivers are on softs.
Force India's Nico Hulkenberg qualified an impressive fifth with Ferrari's Kimi Raikkonen and Sebastian Vettel sixth and seventh -- a disappointment after the team's pace on Friday.
"We were just not quick enough. We were struggling on the supersofts. On the softs we were very good and we were quicker than on the supersofts, which isn't right," said an unhappy Vettel.
Mexican Sergio Perez, the crowd favourite and one of two home drivers in the race, qualified 12th for Force India. Compatriot Esteban Gutierrez, in a Haas, starts 17th.
Neither of the McLarens made it through to the final phase of qualifying, with Fernando Alonso 11th and Jenson Button 13th.
Renault's Jolyon Palmer did not take part at all after the team found a crack in his car's chassis after final practice. The Briton will start at the back of the grid.
"It's really frustrating. We could have been fighting for one of our best grid slots of the year," said the rookie, who is fighting Danish team mate Kevin Magnussen to stay at Renault.
(Reporting by Alan Baldwin; Editing by Andrew Both)
