Lukas Jutkiewicz scored a late equaliser for Coventry to deny Middlesbrough a sixth straight victory.
The striker was on hand to head home off the underside of the crossbar after Roy O'Donovan's shot had been saved.
Marvin Emnes' seventh goal of the season had looked enough to give Boro the three points they needed to take them joint-top of the Championship.
But this would have been harsh on the Sky Blues, who had plenty of possession in the second half at the Riverside.
Coventry boss Andy Thorn opted to stick with the same eleven that picked up the club's first point of the season at home to Watford last weekend.
In contrast, Middlesbrough manager Tony Mowbray made four changes from the side that beat Peterborough in the Carling Cup on Wednesday, with on-loan Carl Ikeme, Rhys Williams, Julio Arca and Justin Hoyte all returning.
It was the home team who made the stronger start. Eight minutes in, Justin Hoyte capitalised on Chris Hussey's error to go through on goal but could only power his effort against the top of the crossbar.
Their fans would not have to wait too long for the breakthrough though.
Again it was Hussey who made a mistake, diverting the ball straight to Emnes, who finished clinically past Joe Murphy.
Soon after, the visitors missed a golden chance to equalise when O'Donovan controlled Matthew Bates' missed interception but could only side-foot the ball over the bar.
It was Boro who finished the half stronger though and Emnes saw a goalbound shot blocked by Martin Cranie before Joe Bennett's 18-yard shot was tipped over by Murphy.
Richard Keogh should have levelled after the break but he could only head Sammy Clingan's corner over the bar with the goal at his mercy.
But with 14 minutes left, Jutkiewicz struck and, barring a late scare when Boro substitute Faris Haroun cannoned a header against the bar, they superbly defended their hard-earned point.