Matty Godden's header cancelled out a howler from Coventry goalkeeper Marko Marosi as League One's top two - Rotherham and the Sky Blues - fought out a feisty 1-1 draw.
Freddie Ladapo put the table-topping Millers ahead from Marosi's mistake but Godden kept the Sky Blues level on points with the leaders and with a game in hand.
Rotherham led in the 23rd minute as Slovakian stopper Marosi dropped Daniel Barlaser's routine corner and Ladapo stabbed home his 13th league goal of the season.
Marosi did make partial amends with a fine fingertip save to prevent Ladapo's classy turn and shot doubling the visitors' lead.
Coventry improved and wanted a penalty when Callum O'Hare seemed to be clipped by Richard Wood when blazing over from six yards.
But the Sky Blues levelled in the 47th minute as Godden, eight yards out, directed home a fine header from Fankaty Dabo's cross for his 12th of the season.
Coventry, now unbeaten in 12 league games, came close to a stoppage-time winner but Godden, unmarked at a corner, headed wide.