The Light Blues have marched into the last 16 of the Europa League after stunning the competition's top scorers Braga at home and away.
While Steven Gerrard's team are going from strength to strength on the continent, they have not hit the same heights domestically.
Gers have dropped 10 points since the winter break and have kissed goodbye to hopes of dethroning Celtic this year.
Supporters and pundits have piled in on the Ibrox men, questioning everything from Gerrard's tactics to the mental toughness of the players.
Midfielder Jack admits his team have had to take that on the chin but he believes Wednesday's 1-0 win at the Estadio Municipal was the perfect response to Rangers' critics.
He said: "It definitely fires us up and it definitely fired me up. I'm sure everyone feels the same.
"When times are tough, people are going to have opinions, they are going to write things and say things.
"We just have to take it. We're at a big club and you have to deal with it. It's important that in the dressing room we all stick together and thankfully against Braga we showed that.
"We're delighted. The boys stuck together, stuck to the game plan and I'm proud of everyone. It was a great night for the club, the players and the supporters.
"The staff had come up with a plan they thought would get the job done and to a man we stuck to that.
"It was a great performance and we could even have scored more. We'll take the win though and look forward to the next round."
Gers will learn their next opponents on Friday but Jack is only focusing on Hearts and Saturday's William Hill Scottish Cup clash at Tynecastle.
He said: "It definitely felt better on Wednesday night. It felt like we were clicking again and everyone was on the same page.
"Braga had to come and beat us as we were winning from the first leg, so it was a different challenge and a different type of game.
"We need to take this feeling into Saturday as we have a chance to do well in the Scottish Cup."