Gary Johnson is promising to conduct a thorough investigation into the late goals which are threatening to undermine Bristol City's Coca-Cola Championship play-off push.

Bristol City came back from a 2-0 half-time deficit to draw level against Sheffield United at Ashton Gate on Saturday, only to lose to a goal scored with virtually the last kick of the game.

Given that the Robins suffered a similar fate in previous games against Preston, Scunthorpe and Peterborough, Johnson has good reason to be concerned by the concession of so many late goals.

But Darius Henderson's last-gasp strike, which came barely a minute after Alvaro Saborio had restored parity, has proved the final straw for the manager, who is now determined to get to the bottom of the problem.

"It's happened to us in four or five games now and this latest one was an absolute killer," said Johnson. "People are asking me why it keeps happening and I can't give an answer at this minute.

"But I'll try to get the bottom of it and I'll go back over all the videos, study them and see if there is a common denominator.

"We worked so hard to get back into the game from 2-0 down and I was pleased when we equalised because I felt we deserved a point. One minute you are happy, the next you are down in the dumps again because you've gone and let in a stupid goal.

"We had 11 men behind the ball from the kick off, someone has made a good run and taken a chance and, somewhere along the line, someone is not concentrating.

"We'll have to look at that. In fact, we probably need to look at everything. There are lots of little things that all add up and I'll do some digging and then try and come up with a reason. It might be that I cannot find a reason."

City's inability to see out a game has cost them at least seven points already this season. And that represents the difference between their current position halfway in the table and a play-off spot.

Johnson said: "It could be a problem with concentration, I don't know. I have to look through the whole team and find out why this keeps happening. Why can't we see out a game? It doesn't seem to matter which team I pick, we keep on conceding in the 90th minute."

City have now conceded seven times in their last two games and most of those goals can be attributed to individual mistakes.

"We have to find defenders and a goalkeeper who can defend for 96 or 97 minutes," added the Londoner. "The lads have got to keep their wits about them, keep concentrating and stay focussed. I am concerned by our defending, but we're not taking our chances either and we have to be better at both ends of the pitch. I thought we defended better as a team than we did at West Brom the week before, but we lost because of the kind of individual errors you cannot legislate for."

Meanwhile, Bristol City are expected to field a side comprising mainly Academy players in tonight's rearranged Gloucestershire Senior Challenge Cup quarter-final at Cinderford.