The best goal of Gary Cahill's career - and, indeed, of Aston Villa's season - virtually ensured that the club will not suffer the indignity of relegation.

But it could be the intervention that puts Birmingham City on a slide towards a place in the Coca-Cola Championship.

The 20-year-old defender scored with an instinctive scissor-kick inside the six-yard area in the 56th minute to put Villa on their way to a 3-1 victory against Birmingham yesterday.

Even Birmingham supporters were seen to applaud a goal that turned the face of a match that hitherto appeared to be heading in Birmingham's direction. At 1-1, Birmingham seemed in control, until Cahill pounced.

Milan Baros, who opened the scoring before Chris Sutton equalised, sealed the victory with a goal in the 78th minute.

Birmingham are back in the bottom three of the Premiership, three points behind Portsmouth, but Villa have risen to 15th position and can breathe more easily.

But while Baros was easily the best player on the pitch, Cahill took the plaudits for an exquisite goal, saying: "I am delighted because this victory is important for a few reasons. It is a local derby, the win means we could be safe from relegation, and the goal is easily the best of my career.

"I am glad I didn't get my head on the ball instead because I wouldn't have got enough power to get a decent attempt on goal. I just tried to get as high as I could and get a good contact on the ball.

"I was falling to the floor just as the ball hit the back of the net and I was surprised. It is especially good that the goal came at the Holte End. I was so pleased for the supporters. I scored one for Burnley last season against Stoke City, a tap-in from one yard out, but never scored anything like this before."

Cahill was cautioned for celebrating with too much enthusiasm but, for once, the sight of a yellow card did not prove to be an inconvenience for Villa.

Cahill's goal, which won a tight match, means that Villa can effectively begin preparations for another season in the Premiership.

The goal has also eased the pressure on David O'Leary, the Villa manager, who is sure to be in charge next season.

Cahill took pleasure in seeing the goal again. Even he was surprised at the quality of it, saying: "One of the staff had it on his laptop and I had quick look at it and it is certainly a goal I won't forget in a hurry. I was delighted. It is a dream come true. But if I had poked it over the line from a yard out I'd have been just as happy.

"It hasn't sunk in that I could get my legs that high. I'll take that booking. I'm not bothered about that.

"There were a lot of important factors around the game. It was important we proved we are the biggest team in the Midlands and we did it in style and the lads worked hard for everyone and the fans were tremendous. It is a great day for everyone, the manager, the staff and everyone involved with Villa."

Aware that his goal might play a significant role in ensuring relegation for Birmingham, Cahill took the professional view.

"It is never nice for teams to go down," he said. "But that's the nature of football. Every game you've got to win whether you are going to put teams down or keep teams up.

"It is important for us to do what is best for Aston Villa and it was important to keep away from that little scrap at the bottom and hopefully now we can look at the teams in front of us and catch a few."

O'Leary, himself a former distinguished centre-back for Arsenal, said of Cahill and Liam Ridgewell in Villa's defence: "Without Olof Mellberg and Martin Laursen, I was a little bit worried for the young lads against two experienced pros. You could feel a goal coming as we weren't winning the first ball. But we had a word in the second half and I felt Gary and Liam Ridgewell dealt with Sutton and Heskey really well. What Gary did at the other end was just a bonus."

Villa play at Wigan tomorrow night and O'Leary has a fitness worry as Steven Davis limped out off with a thigh strain. The injury is not serious but the midfield player might benefit from rest.