Forward Luis Rose scored a hat-trick to sink the Yellows.
It leaves Town two points ahead of Aylestone Park and needing a win over Kirby Muxloe at home in their last match to wrap up a play-off spot.
“We’re naturally very disappointed after that,” said Graves. “We were on top for the first ten or 15 minutes and could’ve taken the lead and then we went and shot ourselves in the foot.
“We said it was imperative that we cleared our lines today because the pitch was very bumpy, particularly in the goal mouths, but we didn’t do it well enough.
“We tried to change a few things as the game wore on, but it was always going to be an uphill battle after the start we made and given who we were up against.
“We’ve got to get back to believing in ourselves and doing what we’re good at, because we’ve stopped in recent weeks.”
One Town player who Graves was keen to praise was Louis Kinnerley who, despite the scoreline, performed admirably as a goalkeeper once again after coming on in the first half to replace the injured Keaton Sharpe.
“I thought Louis did very well,” Graves stated. “He’s so confident and his distribution is excellent.
“We know he’s been a keeper before but he’s still really impressed us when he’s had to fill in. I must admit, in the warm-ups he’s always prepared himself really well and has given me a lot of confidence.
“I certainly won’t have any concerns if we need him to start between the sticks at the weekend.”
But results went their way after Aylestone Park could only draw with St Andrews on Monday.
Hucknall will book a play-off semi-final date with Hinckley if they can defeat Kirby Muxloe.
Graves added: “Saturday’s a massive game. I had a feeling it’d go down to the last game of the season because that’s often the way things work out.
“It’s been a battle this season and we’ve had some high and low points, but what more could a player want than the game we’ve got on Saturday?
“Kirby have had a very good season themselves and will no doubt be difficult to beat, but we’ve got to believe that we can win the match.
“If we manage to get the result we need and get into the play-offs, I wouldn’t fear any of the teams that we could play, but we know we’ll have to perform much better than we did today.”