The top two times in last year's qualifying are the only two laps in the history of the Monaco GP quicker than the 1:11.118 put in by Hamilton in FP2.
To make matters all the more ominous for Mercedes' rivals, Hamilton was able to set his top time on a slightly flat-spotted front-right tyre after a near-miss into Ste Devote.
Hamilton and Bottas were separated by just eight hundredths of a second, with Sebastian Vettel third-fastest on one-lap pace, but eight tenths further down.
Max Verstappen split the Silver Arrows in FP1, but had his running in the second session compromised by picking up debris, missing much of the session, while Charles Leclerc also saw attempts to put in a hot lap affected by traffic.
Alexander Albon was on pace with the Red Bull of Pierre Gasly in the Toro Rosso and his pole position here in Formula 2 last year suggest the Thai could be one to watch in the 'Class B' stakes this weekend.
GPFans is a multi-platform, multi-language brand dedicated to Formula One coverage. We bring you all the ins and outs of the sport, 24/7, everything from up-to-the-minute news and features to the latest viral stories and clips.
We believe that a new generation of exciting, outspoken drivers will make F1 more popular than ever before, and we want to give our users access to as much of their heroes as possible, on and off the track. From Lewis Hamilton to Max Verstappen, Daniel Ricciardo to Sebastian Vettel, we provide in-depth analysis of every every Grand Prix in the season, from Australia to Abu Dhabi.
With Formula One under the new ownership of Liberty Media, how the sport is being covered is evolving, and GPFans will look to be at the heart of this progression into new media, as one of the fastest-growing sites covering the king of motorsports.