Grigg missed a golden opportunity to level the scores midway through the second half as Sunderland slumped to a 2-1 defeat against MK Dons.
Lynden Gooch had won possession deep in the visitors’ half from Dean Lewington, with Grigg turning his low cross wide from just yards out.
It made for a chastening return to the starting XI for Grigg, though Parkinson did say that he believes the striker has made some important strides with his fitness in the last week.
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“Firstly, he worked his socks off for the team,” Parkinson said.
"He needed the game [against Mansfield] last week.
"There had been a couple of times where he was going to play but had just picked up little niggles. Physically I thought he was better today than he was last week.
"He knows it was a bad miss. He is the first one to hold his hand up in the dressing room because he knows those chances have to be made to count.”
Parkinson was asked after the game about the anger in the Sunderland fanbase after what had been a poor display from his side.
Sunderland were dominant in the latter stages of the game, but Russell Martin’s side were more than worthy of the lead they had built.“I am angry and we are all angry,” Parkinson said.
"We made changes for the Mansfield game, some were enforced, some were players decided to give a breather to. Those decisions was made to rest players to try to get a result today but we weren’t able to do that.
“There is probably no team playing football today that has made more clear chances in and around the six yard box than us. If you make that many of those type of chances you tend to win games.
“I keep saying that our expected goals is saying we should be scoring more but we are not taking them. We created gilt-edged chances, but that has been the case in this game as well as others.”