Amid three seasons of dominance for the German team in 2014, 2015 and now 2016, Singapore last year was a rare blip, as Ferrari's Sebastian Vettel won.
"Last year, we got destroyed by Red Bull and Ferrari," Nico Rosberg, Hamilton's Mercedes teammate, said on Thursday.
"They were 1.5 seconds quicker during qualifying and it's huge."
Their team boss Toto Wolff said that Singapore 2015 means Mercedes do not necessarily go into this weekend as the overall favourites.
However, championship leader and 2014 winner Hamilton is more confident.
"Last year we were blown away by the fact that we somehow got it wrong," he is quoted as saying by the local Straits Times newspaper in Singapore. "But a lot of work went into understanding that.
"I definitely think we're not going to have as many problems as we had last year. But if we do, I think we've got the tools to correct it."
Hamilton goes into this weekend's grand prix with a two-point lead over Rosberg.