Australian captain Michael Clarke acknowledged that his team may have lacked a tough edge this series, and he believes Faulkner can instil character to a side fighting to avoid going down as the worst touring Ashes side in history.
Faulkner is the 17th squad member to play on this tour, with Matthew Wade the only man not to play a Test.
Faulkner comes in at the expense of Usman Khawaja, who has averaged 19 this series and has struggled under pressure of batting at No.3.
It's the eighth-straight Test they've changed the batting order and it's an unusual balance for a Test team with two all-rounders in the side.
Faulkner was the shock selection, with Phil Hughes favoured to take Khawaja's role and Wade also mentioned in dispatches.
Clarke made it clear guts and grit got Faulkner over the line.
"He's a wonderful young talent but I think he's got the toughness to mix it with any opposition in any form of the game at the highest level," Clarke said.
"He's a fighter, he's a competitor, he might not look the best all the time but he'll find a way to stay out there and help his partner go on and make a hundred.
"Generally, the better the conditions are for batting the better bowler James is because he's at you all the time and he's extremely competitive.
"I think he's the right character for this team."
Tasmanian bowling all-rounder Faulkner has played eight ODIs and three T20 internationals but is yet to score a first-class century, with eight half centuries at an average of 30.
Faulkner hasn't scored a hundred at any level of senior cricket.
However, with the ball he has averaged 22.87 in the first-class form - announcing himself to Test selectors with a starring role in Tasmania's Shield final win over Queensland.
Faulkner scored 29 not out in Australia's last tour match against the England Lions in Northampton and has only been out once in his past five innings.
As a result he boasts the highest average of the tour, with 82.
Watson will bowl in the match, but Faulkner will help take the load off the team's No.1 all-rounder who is coming back from a groin injury.
It's a bitter blow to Khawaja and Hughes who appear to have a long road back to the Test team.
Khawaja spent two years trying to get back in the side but has been dropped after three Tests.
"As we've seen so far in this series, statistics, records, first class performances haven't meant that much," he said.
"It's about finding a way on that day or over those five days to have success and I know James Faulkner has got the strength to do that."Team: Michael Clarke (capt), Chris Rogers, David Warner, Shane Watson, Steven Smith, Brad Haddin (wkt), James Faulkner, Mitchell Starc, Peter Siddle, Ryan Harris, Nathan Lyon.