Although much quicker than the Briton, Massa recalled Jenson Button's "incredible" fastest lap of the opening day.
Feb.8 (GMM) Felipe Massa emotions were in the brazing zone on Thursday, despite putting Ferrari's new F138 on top of the test timesheets at Jerez.
"It means nothing," said the Brazilian.
"Several teams have very quick and well balanced cars and so I am 100 per cent keeping my feet on the ground."
Indeed, those at the southern Spanish circuit also sensed Massa's caution: a British Sky reporter saying he seemed "downbeat".
And Motor und Sport correspondent Michael Schmidt agreed: "Satisfaction looks different. Felipe Massa sat on his stool in the Ferrari tent for his press conference and conveyed little enthusiasm."
"With the hard tyres, the first day of testing, with the dirty track and everything else ... it was a really fast lap.
"I did not have the car to do that on the first day," said Massa.
"If we are to be in that position at the first race then we need to work -- a lot."
World champion Sebastian Vettel, returning to work with Red Bull on Thursday, also sounded sceptical about Massa's Thursday pace: "Today we left the laptime-hunting to others," he is quoted by Bild newspaper.
Even Fernando Alonso, training in Dubai at present, seems none too interested in Massa's progress. "I have not talked to him," Massa confirmed after Thursday's running.
But the Spaniard wrote on Twitter: "Obviously I'm following the test with the team and I have mails with all info."
Massa agrees that Red Bull is keeping its cards close to its chest, "as they always do".
Lotus, however, is not hiding its optimism. "The car looks fast," said team owner Gerard Lopez, according to Finland's Turun Sanomat, after Kimi Raikkonen ran in the E21 for the first time on Thursday.
"We had a fast car last year but this seems even better," he added.
Finally, Mercedes had a good day at last, with Nico Rosberg putting in a gargantuan 148 laps in the new W04, which on Tuesday and Wednesday failed spectacularly.
"It really put a smile on everybody's face," said the German, who was second fastest.