Hamilton is understood to still be at the circuit, and the team claim he was willing to go along with their decision to give Bottas an entire day behind the wheel. Regardless of the testing program he was on compared with the other two drivers, to outpace them must have felt good.
"Last year I did not perform on the level I should have and I learned a lot from that".
Hamilton comfortably got the better of Bottas as he won his fourth drivers' championship last season, but the Finn says he is not willing to use mind games in his attempts to fight back this year.
Bottas is reportedly facing criticism of having a lack of killer instincts as he is fighting once again for a new Mercedes contract extension after his current deal with the team is set to expire at the end of the upcoming season.
The problem was enough to compromise Max Verstappen's programme, as he did not appear for several hours, following his initial installation lap.
"I would like to put more pressure on Lewis on track and be battling wheel-to-wheel with him more often than previous year", Bottas added.
Hamilton 'sacrificed' time in the W09 to benefit Merc
Asked if McLaren could make it a four-team fight, Bottas replied: "As a team we don't underestimate any team or driver".
Hamilton, 33, was due to test on Wednesday, but the track was closed for much of the morning with the medical helicopter unable to fly in the torrid conditions.
"(Mercedes executive director) Toto Wolff wants us both to be performing on a 100 per cent level, and that can provide some healthy competition".
The weather-affected opening days of pre-season testing have given few concrete clues as to how the pecking order could stand going into the campaign when it begins in Australia at the end of March.
Meanwhile, Hamilton's former team McLaren believe they can compete for podiums after dumping their beleaguered engine partner Honda for Renault.
Alonso (36) spun into the gravel when his right-rear wheel detached from his McLaren.
Although early test runs aren't the be all and end all, Red Bull's new vehicle looks to be pretty fast.
'The track was very cold in the afternoon, meaning it was tough to get any sort of heat into the tyres.