Gareth Southgate admits Middlesbrough were lucky to snatch three points at the end of an "instantly forgettable afternoon" against Derby at the Riverside Stadium.
Tuncay Sanli's 32nd-minute strike was enough to see off dismal Derby - but Boro finished badly and almost paid when Robert Earnshaw missed a golden chance to equalise five minutes from time.
After his team's 1-0 Barclays Premier League win, Southgate said: "We've seen it through today, and they weren't able to punish us - but we can't play like that.
"They should have scored, and we would have been sitting here frustrated again.
"We've got to be better than we were in the second half. We've got to be bolder and be willing to attack more. At the moment we tend to go into our shells, because of the importance of the points.
"Guts has got them over the line, but we have got to be mentally tougher and braver in the way we finish game.
"I think they are learning as a team and scrapping as a team and grafting for each other."
Boro are now eight points clear of the relegation zone.
But Southgate does not consider his team safe yet.
"If we switch off for five minutes at this place we let ourselves down quickly, so we have to drive ourselves on," he warned.
Derby boss Paul Jewell was disappointed after coming into the game in high spirits following the Rams' gutsy performance against Manchester United last week.
Jewell hoped for more from his side, who looked in danger of being over-run in the first period before rallying.
"If we had put in the performance we showed last week against Manchester United I think we might have got something out of the game - but if you perform like that in the first half you don't win matches," he said.
"In the second half we actually looked like we could deal with a football. Hossam Ghaly was a big influence for us. But we just didn't have that killer instinct - and you need that to go with your play.
"It's the story of our season. We did really well against Manchester United and tried to take it into the game today - but we just can't put two performances together.
"We had that golden opportunity right at the end, and that's the difference.
"Teams at the top kill you in a situation like that. But we haven't scored enough, and if you let in too many as well it is a recipe for relegation."