Match ends, Birmingham City 1, Middlesbrough 1.
Patrick Bamford scored a second-half equaliser as Middlesbrough survived the dismissal of goalkeeper Dimi Konstantopoulos to earn a point and go top of the Championship.
Konstantopoulos was sent off for bringing down Birmingham striker Clayton Donaldson in the 43rd minute.
Paul Caddis drove home the spot-kick to give the Blues a deserved lead.
Boro hit back after half-time and equalised after 74 minutes when Bamford fired in his 12th goal of the season.
The draw ended Boro's run of six successive Championship wins but was enough to take them above Derby and Bournemouth and into top spot.
Aitor Karanka's side, bouncing back from their FA Cup exit at Arsenal last Sunday, went close early on as Darren Randolph finger-tipped an angled shot from Emilio Nsue.
But Birmingham, with four draws and a defeat from their previous five league games, were on top for the remainder of the first half.
Andrew Shinnie saw a long-range effort saved by Konstantopoulos, while Donaldson was a constant threat.
And it was Donaldson's pace in getting first to a poor back pass from Ben Gibson that saw him knock the ball past Konstantopoulos before being tripped by the Boro keeper, who was shown the red card.
Replacement Tomas Mejias, who came on for striker Jelle Vossen, was unable to keep out the penalty from Caddis as Birmingham led at the break.
But former Boro full-back Jonathan Grounds and winger David Cotterill missed chances early in the second half.
And the visitors then built up some pressure, earning their reward when the impressive Grant Leadbitter slipped through a pass from the edge of the penalty area for Bamford to calmly slot a low shot past Randolph.
That gave Boro the result they needed to head the promotion race, although they were almost denied in stoppage time when Donaldson headed a Caddis cross over the bar from six yards out.
Middlesbrough manager Aitor Karanka told his club's website:
"I'm very proud of all the players. They know that and I told them after the game that finally we're at the top of the table and we are there because all of them deserve it.
"After 31 games we're at the top and I don't know if anyone thought we would be in this position back in June or July.
"Now we have to defend this position and it's going to be very difficult. This league will be tight until the end.
"We're top of the table but we will be making a mistake thinking everything is done. All the players are doing really well so we have to enjoy being in this position and defend it now."
Birmingham manager Gary Rowett: "Had you of asked me before the game would I be pleased with a point I would have said of course but after Middlesbrough going down to 10-men and being 1-0 up I am disappointed we did not take all three points.
"As for off the field concerns, and the potential deduction of 10 points,
"I can't control that and I said that to the players. Off the pitch we can't control what happens.
"The news the days before the game I just think it spread a bit of negativity among the staff and the players initially.
"But if it needs to be done to move the club forward so be it. We just have to concentrate on what we do.
"If the worst comes to the worst and we lose 10 points, which I don't think it will, we will crack on. I don't think it will come to that. I think the club is financially stable."
- 26DavisSubstituted forReillyat 60'minutes
- 11CotterillBooked at 42mins
- 22ShinnieSubstituted forThomasat 77'minutes
- 33GraySubstituted forDyerat 69'minutes
- 13KonstantopoulosBooked at 43mins
- 5FredericksBooked at 56mins
- 22OmeruoBooked at 90mins
- 10TomlinSubstituted forReachat 85'minutes
- 24NsueSubstituted forAdomahat 62'minutesBooked at 88mins
- 21VossenSubstituted forMejiasat 45'minutes
- David Coote
- Shots on Target
Second Half ends, Birmingham City 1, Middlesbrough 1.
Kenneth Omeruo (Middlesbrough) is shown the yellow card for a bad foul.
Foul by Kenneth Omeruo (Middlesbrough).
Stephen Gleeson (Birmingham City) wins a free kick in the attacking half.
Attempt missed. Clayton Donaldson (Birmingham City) header from very close range is just a bit too high. Assisted by Paul Caddis with a cross.
Foul by Patrick Bamford (Middlesbrough).
Jonathan Spector (Birmingham City) wins a free kick in the defensive half.
Corner, Birmingham City. Conceded by Albert Adomah.
Delay over. They are ready to continue.
Delay in match Grant Leadbitter (Middlesbrough) because of an injury.
Albert Adomah (Middlesbrough) is shown the yellow card for a bad foul.
Foul by Albert Adomah (Middlesbrough).
Jonathan Grounds (Birmingham City) wins a free kick in the attacking half.
Foul by Patrick Bamford (Middlesbrough).
Paul Robinson (Birmingham City) wins a free kick on the left wing.
Substitution, Middlesbrough. Adam Reach replaces Lee Tomlin.
Foul by George Friend (Middlesbrough).
Jonathan Grounds (Birmingham City) wins a free kick in the defensive half.
Corner, Middlesbrough. Conceded by Paul Robinson.