Fulham came from behind to draw 1-1 through Ivan Cavaleiro's late header, as Parker's side made it five League games unbeaten.
Parker was incensed at the Premier League's decision to reschedule the fixture at 48 hours' notice after "10 or 11" of his squad spent 10 days in isolation before Saturday's FA Cup tie with QPR.
"It's been a tough couple of weeks," said the Fulham boss. "A game that got put in our laps on Monday morning — we used that, of course we did. We felt it was unfair, we didn't think it was right, so that helped.
"I thought to a man we were superb under what we faced: a lot of speculation, a lot of talk from outside, but no one really knows the full extent of what we've been through. Players out there who have had one day's training after coming back from illness, players in the squad that have had two, three, four days' training."
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