The Lions attacker was a surprise starter but seemed to lose all interest in the game shortly after a burst down the wing. From the stands it wasn't clear why manager Kenny Jackett took the player off after a short discussion but the Millwall boss was at pains to point out that Grabban did the right thing by informing him that he'd tweaked his hamstring yet again.
"He has not done it too badly but he pulled up straight away and came off to the side of the pitch," Jackett told the Southwark News. "Maybe his body is on overload and it is its way of saying that he needs a rest to get it right.
"He has not been himself of late. Maybe for a few games, he has not had the real burst that we saw in him in the first half of the season. He made one run on Tuesday and it was a flash of the Lewis Grabban that we had got used to.
"Maybe a break might help him come back to the form we know he is capable of. If he needs a spell out, then we will give him it to assess him and get his body right."
Grabban, who was signed from Crystal Palace, has been the centre of controversy recently after the same newspaper reported that he had been targeted by Millwall fans during the away win at Hereford United. However, this was denied by those present at the game and the story has been ridiculed by many involved with the club but the whole incident seems to have affected the youngster, a fact recognised by Jackett after the substitution was booed.
"It was just frustration from the crowd with the way the game was going I think," he continued. "People can see and know what he can do, not just this season but the end of last as well. He has been a match-winner for us at times and it's the crowd's growing frustration that it's not quite happening for him - a possible match winner.
"He couldn't carry on, you cannot run those things off. Like a lot of quick players, they can struggle with muscle injuries particularly in hamstring area as they are always on the edge.
"But he is just 21, its his first full season in league football and he will come through it."