Rangers triumphed at Stamford Bridge for the first time in three decades when Shaun Wright-Phillips fired an outstanding 78th-minute winner in a 1-0 victory against his former club.
It was a precious three points that could yet prove pivotal to the club's Barclays Premier League survival bid and, while they remain at the foot of the table, hope has returned to Loftus Road.
Just hours earlier Redknapp had been lamenting the decision of Liverpool playmaker Cole to reject QPR in favour of returning to boyhood club West Ham.
"I lost Joe who would have been my first signing. He probably looked here and thought, `Harry, I love you, but you're not going to stay up'," Redknapp said.
"I like Joe and he would have been good for me. He's West Ham and they love him there. I thought he was coming for sure but West Ham came in (on Wednesday)."
Only goal difference separates QPR from 19th-placed Reading and while they remain five points away from safety, Redknapp hopes the conclusion of their three-match losing streak will provide the springboard to climb the table.
"That was our first away win in the league since October 2011. Let's hope we can build on it. There's still a long way to go but that was encouraging," Redknapp said.
"Everybody else thought I was mad but I do genuinely believe we can stay up. We're not doomed, we can turn it around.
"I said to [assistant coach] Joe Jordan after the game, `I cant remember having many better games than this one'."