Sunderland drew 1-1 at home to Blackpool on Tuesday night.
The Black Cats were looking to get back to winning ways after drawing at Oxford United on Saturday, but were left frustrated again.
After missing a couple of decent openings, Sunderland went behind when Blackpool striker Armand Gnanduillet rocketed a left-footed shot into the bottom corner.
Sunderland rescued a point when Jack Baldwin powered home a header with 15 minutes to play, and 1-1 is how it finished as Sunderland suffered disappointment.
They sit four points adrift of the automatic promotion spots, and all the talk will be about Grigg's shocking miss in the second half.
Grigg rounded Blackpool goalkeeper Mark Howard, but with an open goal at his mercy, he somehow contrived to put the ball wide of the target.
Grigg also fired straight at Howard with a big first half chance, and Sunderland fans may have expected their new big-money addition to score both chances.
Ross spoke after the game and wasn't too harsh on Grigg, noting that he'd score both chances 99 times out of 100, but the great thing is that he's getting opportunities to score – and added that he's 'a bit sore'.
“The two clear-cut opportunities he had, the first just prior to their goal and then the one in the second half, I think he would back himself 99 times out of 100 to take - particularly the second one,” said Ross. “But the great thing for me is that he is getting in those positions and if we can keep getting him in those positions and creating opportunities, he will score goals because his track record suggests nothing else.”
“He’s a bit sore but we still managed to get something from the game, however he knows he could have marked his home debut tonight with a couple of goals,” he added.