Head coach Alan Solomons lamented the mistakes that cost Edinburgh in the first leg of their
20-16 home defeat
in the 1872 Cup match against Glasgow.
"It is very disappointing because I thought it was a game that we could, and should, have won," said the 63-year-old South African.
"I thought we were certainly on top in that first half; it was just some penalties that cost us field position.
"In the second half again it was errors."
Edinburgh had been enjoying the better form going into the festive double-header against their rivals from the western side of the M8.
The matches for the 1872 Cup double as Pro12 matches, where Solomons' side were hoping to register their fifth win in six games.
Dougie Fife's converted try and three Greig Laidlaw penalties had given them a 16-9 half-time lead and they might have been further ahead after that had they not fumbled the ball five metres from the try line out on the left wing.
However, they were caught out in 68 minutes when Alex Dunbar fed DTH van der Merwe near the halfway line and his kick through the Edinburgh defence was landed on by the rampaging Stuart Hogg for a try.
"We took a beautiful ball from the line-out, made 10 yards over the gain line and then lost that ball, which ultimately led to their try," said Solomons.
"It was a try apiece. They took their chance and well done to them.
"It came from a turnover, when obviously our defence is at sixes and sevens because we've just taken the ball into the line-out and we've lost it and they got the bounce so fair play to them.
"They had the upper hand at the breakdown in the second half. I've got to have a careful look at what went on.
"Derby games are always tough games and they always turn on one or two things. This game turned on a turnover."
The teams meet again at Scotstoun Stadium on New Year's Day, with Glasgow third in the Pro12 on 33 points and Edinburgh 11 points behind in seventh spot having played a game more.
"It will be the same next week," added the head coach.
"Little things are going to make the difference in this game."