Marc McNulty's controversial goal and a Jack Grimmer header saw Coventry maintain their winning start to the season with a 2-0 win at Grimsby.
After his hat-trick on the opening day of the season, Jodi Jones almost got himself back on the scoresheet as he cut in from the wing, but James McKeown managed to get a strong hand to the shot to keep things level.
Coventry took the lead in bizarre circumstances in the 63rd minute, as Nathan Clarke seemingly rolled the ball back to McKeown to take a free-kick, only for McNulty to take it and run towards goal before rolling into an empty net.
There were no questions about the second though, as Jack Grimmer rose highest at a corner to head in the visitors' second after 76 minutes and secure their second win in their opening two league games.
The hosts' misery was compounded when midfielder James Berrett picked up a second yellow two minutes from time, resulting in Grimsby second red card of the season.