The Mercedes driver was trailed by both the Ferraris of Sebastian Vettel and Kimi Raikkonen, with his championship rival and team mate Nico Rosberg only able to muster a time fast enough for seventh position.
Home favourites Sergio Perez and Esteban Gutierrez had differing sessions, ending the session in fourth and 15th respectively.
Rosberg initially had the upper hand in the early part of the session at a cold Mexico City, with ambient temperatures only peaking at 13° - thus rendering this morning's session inconclusive.
However, his early time of 1:22.748 was good enough to top the timing sheets provisionally, but no more than three minutes later, Hamilton bested his efforts by eight tenths.
The high, 50mm curbs around the circuit caused disruption to the session a fraction past the half hour mark, with Felipe Nasr running wide in his Sauber on the exit of the twisty Esses section, bouncing over the rumble strips, before the right side of his front wing was lunched by his left front wheel and spat out all over the circuit, with Kevin Magnussen having to take sudden evasive action in his Renault.
Flustered, the Brazilian reported over the radio he "felt a funny noise". Indeed.
And thus, that brought out the red flags for six minutes whilst the detritus from the eye-catching failure was cleared.
Having spent most of the morning in the pitlane, Raikkonen set his fastest lap at the end of the session as the cool track started to rubber in. A 1:21.072 was good enough for third, 0.79 seconds off of Vettel in the sister Ferrari.
Finally, a spark of light for the faltering Italian team, having suffered yet another disappointing weekend in Austin. Fortunately, Raikkonen's bizarre retirement only incurred a small monetary fine, not a grid penalty for Sunday.
Keeping on the battle for second in the Constructors' Championship, Daniel Ricciardo and Max Verstappen could only manage eighth and 14th in their Red Bulls. More alarmingly, Verstappen's left rear brake caught fire in the pitlane, all but ending his morning prematurely.
For the most part, the medium tyres - Pirelli's hardest compound this weekend - were causing difficulties. With track temperatures only reaching 23°, it took several laps to heat them up sufficiently. Undeterred, Hamilton managed to switch them on for his second run, venturing closer to the 1:20 mark, a 1:21.5 was the benchmark he set just before the hour.
Moments later, he found even more, settling on a time of 1:20.914, one he didn't attempt to beat for the last half hour. It was around seven tenths faster than last year's fastest lap in this session, despite lower grip levels.
Further down the order, Daniil Kvyat spun late on at Turn 1, citing a problem with the rear balance of his Toro Rosso, and ended up tenth fastest, Carlos Sainz followed in 12th, with the Haas of Romain Grosjean sandwiched in between.
McLaren surprised on speed trap figures, with Fernando Alonso in the top five - but it failed to reflect on their lap times. Alonso in 16th, Jenson Button in 18th. Button reported a funny noise coming from the engine, followed by voice-altering vibrations after the chequered flag dropped.
|4||Sergio PEREZ||Force India||1:21.200||+0.286||23|
|5||Nico HULKENBERG||Force India||1:21.409||+0.495||23|
|8||Daniel RICCIARDO||Red Bull||1:21.727||+0.813||27|
|10||Daniil KVYAT||Toro Rosso||1:22.215||+1.301||29|
|12||Carlos SAINZ||Toro Rosso||1:22.563||+1.649||32|
|14||Max VERSTAPPEN||Red Bull||1:22.877||+1.963||10|