The SPFL Premiership newcomers missed the chance to go top of the table on Friday night as Hearts left it late to nick a point at Firhill, Jamie Walker netting just minutes after Muirhead had fired the hosts ahead from the penalty spot.
While the Jags were rightly disappointed at letting two points slip away, they have still enjoyed a terrific return to Scotland's top tier, taking five points from their three games against Dundee United, Ross County and the Jambos.
Thistle were at their free-flowing best against Gary Locke's side and Muirhead reckons boss Archibald deserves all the credit for his attack-minded approach.
He said: "At the start of the season, if you had offered us five points from three games we would have taken it, but looking back at the games, we are unlucky not to have nine points on the board and at least another win.
"I don't think anyone is looking behind them. We are only looking up the table. We are a young team and I think that helps us, we are fearless.
"I think we have caught people by surprise with the way we have played. We will keep playing our football and show we are good enough at this level.
"We have to play to our strengths. We have got great players going forward and our full-backs always push on as well. There is no point in us sitting deep.
"The manager has instilled a belief in the squad that we can go and play our way. A lot of credit has to go to him. He has the faith in us to go and express ourselves and he is putting in a lot of work behind the scenes."
It was a case of what might have been at Firhill on Friday night as Thistle dominated, much of what was an entertaining encounter, but couldn't make sure of all three points.
And Muirhead is determined the Jags will bounce back from their late heartache at the first opportunity when they head to Fir Park this weekend aiming to continue their unbeaten start to the campaign. He said: "We dominated in the first half and were unlucky not to be ahead. Hearts came into it in the second half, but didn't create many chances.
"When we went 1-0 up, we had to see the game out so for it to end like it did felt like a defeat. Hopefully we can get a win on Saturday at Motherwell.
"It will be another tricky game. They will be one of the top teams this season and this will be one of the toughest games.
"They have lost a few players from last year, but they have made a few good signings as well."