England batsman Michael Lumb believes the absence of Mitchell Starc, who has been on international duty for Australia, has left a gaping hole in the Sydney Sixers team.
Starc was the leading wicket-taker in the recent Twenty20 Champions League and was central to the Sixers triumph in that tournament.
"It's a huge loss," Lumb said on Friday.
"You look at the success he's had in the previous games and in the Champions League - it's a huge hole.
"He's just a super talent - he's got good pace, gets the ball swinging around and at the death he executes the yorkers, so he's an all-round package."
Lumb, who was the leading run-scorer in the Champions League, says the mood is still upbeat in the Sixers camp despite four defeats on the trot.
The defending champions are focused on beating Sydney rivals the Thunder at ANZ Stadium on Sunday night and are desperate to earn back a bit of pride.
"Both Sydney teams have struggled, (so) we're both in the same boat," Lumb said.
"(There's) a bit of pride at stake, we'll try go over there and knock them over."
The Thunder have had another woeful Big Bash League campaign, but they've brought in England's dangerous wicketkeeper-batsman Matt Prior.
Lumb has chatted to his Sixers team-mates about Prior's 'secrets' and he believes they have the goods to combat him.
"He (Prior) is a good all-round player," Lumb said.
"(He's) pretty destructive, a good, clean timer of the ball and he can take the game away from people."We've got a few plans for him."