SYDNEY, AUSTRALIA - JANUARY 01: Jos Buttler of the Thunder bats during the Big Bash League match between the Sydney Thunder and the Hobart Hurricanes at Spotless Stadium on January 1, 2018 in Sydney, Australia. (Photo by Brett Hemmings/Getty Images)

Sydney Thunder have secured the signature of England's Test captain Joe Root, along with big-hitter Jos Buttler for BBL08.

The confirmation of the British duo signing on ends all speculation Jamaican allrounder Andre Russell will be making a return to the lime green for the upcoming Big Bash season.

However, the Thunder will need to sign alternative internationals for the second half of the competition as Root and Butler will be called upon for national duties.

The pair will be available in the early stages before heading to the Caribbean to be apart of the England squad.

Buttler has been one of the most exciting players to hit a white ball in the modern day, and recently torn Australia apart in a five-match series, and is carrying that form into Test cricket, scoring his first century last week against India.

Astonishingly, Root hasn't competed in a T20 competition outside of England, after being snubbed in this years IPL auction.

The Big Bash will be the latest taste of T20 cricket for Root, who too was omitted from England's T20 side, showing the depth of talent they possess in the limited-over format.

Root will be looking to boost his case for a national recall via impressive performances for the Thunder, while the signing of Root will also attract many fans as they'd get the chance to witness a glimpse of the high-profiled player.

The 27-year-old said the reporters he wants to gain as much experience in T20 cricket as he possibly can.

"It's one of those tournaments where you want to be involved in it and I'm really excited to get that opportunity now with Sydney," Root said.

"I'm sure there will be some mixed emotions for the fans (with me signing) but … hopefully I can win them over through the time there.

"There's an opportunity for myself now to put in some strong performances and help Sydney Thunder go on and do some special things this year."

Buttler, who was apart of the Thunder's squad in BBL07, quickly became a fan favourite last year after averaging 33.66, scoring two half-centuries in six games.

Also at the age of 27, Buttler said he's loved his time and the atmosphere at the Thunder and wants to continue on with the team.

"There's a lot of young guys but some experience in there as well, including Shane Watson who I really got to enjoy getting to know and playing under his captaincy," Buttler said.

"It's a great part of the world and a really fun dressing room. I'm delighted to be back with the Thunder Nation."

Thunder coach Shane Bond use to be an assistant coach to the English Cricket Team, and has used those connections to lure the duo to Sydney, stating to News Corp Root will have a massive point to prove.

"There's a lot of talk about his T20 game. I think he's a fantastic T20 player and he's hungry to make a point on that," Bond said.

"I've seen him play amazing innings in T20 World Cups and he played for Yorkshire this year and scored 50 off 20 balls. He's one of the finest players in the world.

"You want to get guys who are hungry to succeed and have a desire to play at the highest level or win World Cups … and both Jos and Joe fit that bill and we're lucky to have them.

"We had a team that was pretty close to (finals) last year. Now they're a year wiser and older and having Jos and Joe (makes it) a pretty good-looking side."

Root and Buttler are the only two internationals signed to the Thunder, and they still have another six positions in their roster to fill before BBL08 starts.