St Kilda Captain Jarryn Geary believes the Saints let themselves down in Sunday’s must win game against Melbourne, with the loss all but ending their finals aspirations.

With a top-eight spot up for grabs, the Demons made the faster start at the MCG before withstanding a fightback in the second half to leap from 10th to 7th, while the Saints remain a game and percentage outside the eight in 11th.

Geary, who signed a one-year contract extension on Tuesday that ties the small defender to the club until the end of 2019, said the Saints were bitterly disappointed with their performance but must use the next two weeks to improve.

“Call it what you will, we just didn’t perform the way we want to perform, especially in that type of game,” Geary told reporters at a press conference at Linen House Centre on Tuesday.

“We set ourselves for a big game but we didn’t perform the way we wanted to and that’s the disappointing thing about it.

“It obviously wasn’t a positive review, our performance on the weekend wasn’t a very good one; we let ourselves down in a number of areas.

“We’ve had an opportunity to look at that now and we can use the next two weeks to try and improve some of the stuff we dished up on the weekend.”

Geary said St Kilda was punished for allowing Simon Goodwin's team to put the foot down early and open up a five-goal advantage by quarter time, which would ultimately be more than the margin at the final siren.

“When you give a team a five-goal head start on the back of your contest and your defence, you’re going to be in for a pretty tough day,” Geary said.

“They came out and blew us off the park early and we didn’t respond until really until after half-time when we had a relatively positive third quarter, but by then it was too late.”

The 29-year-old doesn’t think St Kilda’s preparation was to blame for the lacklustre start at the MCG on Sunday.

“I thought we prepared really well,” Geary said. “You can’t get into the 21 players minds and see what they’re thinking. But it felt like we were invested in trying to get a really good result for the football club but obviously it turned out otherwise.”