St George Illawarra's NRL premiership hopes could hang on a knife's edge.
The Dragons will nervously await the results of scans on Gareth Widdop's shoulder after he dislocated it in the first half of their shock 40-4 loss to Parramatta on Saturday.
Widdop injured his right shoulder when he awkwardly attempted to ground a Mitchell Moses grubber, only to trudge off and be ruled out for the rest of the match.
Asked how Widdop was after the match, McGregor said: "Not good.
"His shoulder's popped up and come back in. He'll have a scan tomorrow."
The Dragons co-captain could be ruled out for the rest of the season if scans show major damage to the shoulder.
"The performance manager's told me then - it's popped up and gone back in, which is great. I hope scans tell a similar story (on Sunday)," McGregor said.
Widdop's health isn't the only worry for McGregor after what he conceded was arguably their worst effort of the season against the Eels.
Ladder leaders for most of the year, the Dragons compounded ill-discipline with soft defence that allowed the Eels to run in their biggest score of the year.
"You're playing against a side running 16th and they put a score on you. Just disappointed with some areas of our game at the moment that we need to fix," McGregor said.
"You can't have that many errors in the game, we let some really soft tries in the game .. We're all disappointed. I'm the leader of that group so I'm the most disappointed."
The result not only means the Dragons drop out of the top four for the first time this year, but are now just two points ahead of eighth-placed Brisbane.
McGregor hit out at the possibility of finishing the year outside the top four.
"Let's look at that in three weeks time because at the moment we can still make the four. There's three games to go," he said.
"We can't get that back, we've got three to go. We can certainly do something about the next three games and if we do something about that we'll be in the four."