Misfiring Aaron Mclean faces an intensive week at training to try to rediscover his scoring boots.
Mclean fired another blank on Saturday as City were stunned by lowly Stevenage at Valley Parade.
Two superb strikes from midfielder Luke Freeman took them off the bottom of League One after coming from behind to win 3-2.
Both his goals came after Mclean had spurned a glorious chance to put City two up early in the second half.
The striker is still to get off the mark in eight attempts since being signed as the replacement for Nahki Wells.
Phil Parkinson admitted it is becoming a concern and City will focus their efforts in practice on trying to restore Mclean’s confidence in front of the net.
Parkinson said: “There was nothing wrong with his all-round effort. I thought he put in a good shift for the team.
“He set the tone with his closing down right at the start of the game.
“But strikers thrive on goals and he can’t hide away from the fact that he hasn’t got his first one yet.
“Obviously he’s frustrated and it looks like he is snatching at things.
“The only way (to solve that) is to work hard on the training ground, to concentrate and for us to make sure we’re giving him as much work in and around the penalty box as possible.
“If he’s scoring in training, he can take that into the game.”
McLean was not the only guilty party as City blew the chance of a third straight home win. Sub Mark Yeates also fired wide from close range when he seemed certain to equalise.
A bad day was compounded with the loss of Andrew Davies with a calf injury, sparking fears that he could be sidelined for another significant spell.
City’s advantage on the bottom four was cut to six points because of Bristol City’s win – and they head for promotion-chasing Brentford next.
Parkinson added: “We lacked a bit of composure in the second half in our all-round play. I don’t know whether that was an expectancy to win or Davies going off which unsettled the balance of the team.
“When we play at our best, we have a good balance in our team going to our front players but also playing through the midfield.
“We didn’t get that right. It just needed someone to calm us down on the ball, pick a right pass and there wasn’t enough of that.
“There’s an element of frustration but when you’re not playing great, you do need that third goal.
“We had a massive boost with the two wins and this is a setback again for us. But we’ve got to go again. The dividing lines are so tight and we’ve lost the game to two terrific strikes. We’ve had the chances to have killed the game but didn’t take them.”
City had led twice in the first half through Adam Reach and James Hanson.
Reach, whose volley was the first goal of his loan spell, said: “It’s very frustrating. They were bottom for a reason and don’t often come back and win games.
“We thought the game might have been won already at half-time and that was our downfall.”