Having led the way for most of the Irn-Bru First Division campaign, the Jags have slipped from the top of the table after a defeat to promotion rivals Morton and draw at Airdrie.
They host a resurgent Accies today as they look to kick off 2013 in positive fashion, and McNamara is determined to get back to winning ways.
He said: "It is disappointing to come out with only one point from the last two games after putting so much into them.
"But that is football. You have got to take your chances. We can't just turn up and expect to win games.
"The Airdrie match is one we should be winning, but we didn't start well enough and apply ourselves.
"We knew we couldn't feel sorry for ourselves after the Morton game, but we weren't good enough early on in Saturday's match.
"We don't want to drop points in three successive games. They are all big games for us, every point is massive.
"It is the same right across the league, every team has got their own fight to win. Airdrie are down at the bottom fighting for their lives, as Hamilton were the last time we played them.
"They went 4-1-4-1 at home against us and they have picked up in recent weeks and got results.
"I imagine they will come to Firhill and set up in the same way, try to frustrate us, chase lost causes and catch us on the break.
"It comes down to how you set about teams.
"We have had chances in the last couple of games that we haven't taken and you need things to go for you on the day.
"There are things you can't control, like decisions or bad luck."
Thistle have endured mixed fortunes against Billy Reid's side this term, winning 4-0 at Firhill but losing twice on the road.
McNamara returns to the dugout this afternoon after a ban for being sent off at New Douglas Park in November.
And he has been boosted by the news that striker Steven Craig will be staying at the club until the end of the season.
Craig, who has bagged seven goals in 12 games, had been on loan from Ross County, but that deal expired at the weekend.
Now Thistle have moved fast to make the player's move permanent.
A club spokesman said: "We are delighted he has now signed a deal that will keep Steven at Firhill until the end of the current season at least.
"He is sure to be a crucial player in the second half of the season."