Hibernian manager Alan Stubbs bemoaned his side's lack of discipline after they lost the first Edinburgh derby of the season 2-1 to Hearts at Tynecastle.
Both sides were relegated from the Scottish Premiership last season but opened their Championship campaigns with wins last weekend.
The passion on show from both sides made for a frantic encounter but the match appeared to be heading for a goalless draw until Sam Nicholson's wonder strike fired Hearts in front.
Any hopes Hibernian had of winning the first capital league derby to be played outside the top flight were then ended when Scott Robertson's moment of madness resulted in a red card and a penalty after he pushed Prince Buaben in the box, with the Hearts man converting the spot-kick himself.
Farid El Alagui did pull one back for Hibs in stoppage time but rookie manager Stubbs was frustrated that his side had contributed to their own downfall.
"I didn't think there was an awful lot in the game. I thought we were controlling it and they weren't hurting us," said Englishman Stubbs, who joined Hibs in the summer.
"We were doing what we wanted to do and were keeping their fans quiet and probably a little bit of ill-discipline has cost us.
"The penalty was a penalty and the lad has had a good strike but it's disappointing, it really is, as I don't think the scoreline reflected the game."
Things might have been different if Hibs had scored from the spot after they had earned a disputed first-half penalty.
Hearts debutant goalkeeper Jack Hamilton collided with Danny Handling as he came to punch a ball clear and referee Willie Collum adjudged the Hibernian player had been fouled despite the 'keeper appearing to have got a touch on the ball first.
However, Hibs failed to take advantage as Liam Craig sent his spot-kick wide.
"These things can happen in games and it's how you respond that's important. For 10 or 15 minutes after it we let it affect us too much," Stubbs added.
- Passion spilled over -
Hearts head coach Robbie Neilson, who also saw his side reduced to 10 men after Osman Sow was given a straight red after catching Michael Nelson in the face with an elbow, admitted tempers had boiled over at times in a fiery encounter.
"It's a passionate game. Both teams have a new impetus and confidence at their clubs and both were coming here wanting to win the game," said Neilson, whose side move level on points with leaders Queen of the South and three clear of both Hibs and Glasgow giants Rangers following their third straight derby win.
"I think the passion has spilled over a little bit. We spoke before the game about wanting to remain level-headed and we let ourselves down a little bit on that side of things.
"But it's great to get the win after Ibrox last week. We were probably favourites coming into the match and most of the pressure was on us. I think we handled it well and I'm delighted."
Hearts handed young 'keeper Hamilton his debut after first-choice Neil Alexander suffered a broken cheekbone in the victory against Rangers at Ibrox last weekend and back-up Scott Gallacher was injured in training.
"I had no issues at all about putting him in. We spoke about bringing in someone else but I wanted to give him a chance," Neilson, a former Hearts youth coach, said.
"I worked with him a lot last year and he has a fantastic character and I thought he could have been man-of-the-match today.
"It's a really intense atmosphere as it's a big derby and he handled it like a seasoned pro."