Sydney Sixers
Captain: Moises Henriques
Coach: Greg Shipperd
Overseas players: Tom Curran (England), James Vince (England)
Full squad: Moises Henriques, Sean Abbott, Justin Avendano, Jackson Bird, Tom Curran, Ben Dwarshuis, Jack Edwards, Mickey Edwards, Dan Fallins, Josh Hazlewood, Daniel Hughes, Nathan Lyon, Steve O'Keefe, Josh Philippe, Lloyd Pope, Jordan Silk, Steven Smith, James Vince.
Last season: Semi-finals
A solid league season helped them qualify in third place for the semi-finals, a run of four victories in a row in the latter part of the tournament building a good head of the steam. But that was halted in the final regular season game when they collapsed for 74 against the Stars. That blew the chance of a home semi-final, meaning they headed back to Melbourne to face the Renegades, where Dan Christian ripped the match from them.
What's changed for the season?
It has been a reasonably quiet off-season for the Sixers, although there was the headline of them securing Steven Smith for a handful of matches at the back-end of the tournament, which could include the finals if the Sixers make it, while Josh Hazlewood has also returned after a gap of five years. They may need to look for overseas replacements at that stage, however, with Tom Curran and James Vince likely to be involved in England's limited-overs matches in South Africa.
Australia impact
Alongside Smith not appearing until after the one-day tour of India, Nathan Lyon and Hazlewood won't be available until the Test series against New Zealand ends, and Hazlewood could be delayed further if recalled to the ODI side. But apart from that only a potential call-up to the one-day side for Sean Abbott would disrupt their plans.
Player to watch
Josh Philippe passed 300 runs last season but that still felt a little underwhelming for the talent he possesses. At 22, he still has plenty of time on his side, but a strong campaign this year could propel him into the planning for next year's T20 World Cup. After a promising start to the Marsh Cup for Western Australia, he was left out of the final, so the BBL will be crucial for keeping the season on track.
Key stat (Gaurav Sundararaman)
Daniel Hughes has been the most consistent batsmen for the Sixers in the last three seasons. He has scored more than 200 runs in each of the last three seasons averaging in excess of 30. His strike rate over the last three seasons (121), however, is the lowest for a top-order batsman to have played a minimum of 400 balls.
Sydney Thunder
Captain: Callum Ferguson
Coach: Shane Bond
Overseas players: Alex Hales (England), Chris Morris (South Africa)
Full squad: Callum Ferguson, Jono Cook, Oliver Davies, Matthew Gilkes, Chris Green, Alex Hales (overseas), Usman Khawaja, Jay Lenton, Nathan McAndrew, Chris Morris (overseas), Arjun Nair, Alex Ross, Daniel Sams, Gurinder Sandhu, Jason Sangha, Tanveer Sangha, Chris Tremain
Last season: 6th
They were in contention throughout the competition before falling just short of the knockouts. There was an element of controversy to that as they were well on top in the match against the Brisbane Heat at the Gabba when the lights went out. A brilliant century from Callum Ferguson secured a big chase against the Perth Scorchers but they were thrashed by the Sydney Sixers to all but end their hopes.
What's changed for the season?
There have been two strong overseas signings in Hales and Morris, while Chris Tremain, after his move from the Melbourne Renegades, bolsters the pace attack, which had been a weakness. Alex Ross has also come in from the Brisbane Heat.
Australia impact
Usman Khawaja, who has committed his future to the Thunder, may be available for the whole campaign after losing his Test place, although he could still feature in the ODI squad to tour India in mid-January. Pat Cummins, who played once last season, will not feature this season.
Player to watch
Matthew Gilkes is a rising star, having given glimpses of his talent for New South Wales this season to follow his 51 off 38 balls on T20 debut for the Thunder last summer when the club went through a succession of wicketkeepers. With Jos Buttler not returning, there is a chance for someone to grab hold of the wicketkeeping spot, and Gilkes will compete with Jay Lenton although he could also play as a batsman.
Key stat (Gaurav Sundararaman)
Since the start of 2017, there have been 157 bowlers who have bowled more than 200 balls in the powerplay. Chris Green has the best economy rate (6.04) for a spinner and the second best among all bowlers, only behind India's Bhuvneshwar Kumar (5.89). With the T20 World Cup in Australia next year, Green's performance will hold the key towards Thunder's hopes as well as his chances to make the Australia squad.