Welsh coach Dai Young has demanded a significant improvement from the Baa-Baas after their heavy 40-12 defeat to England last Sunday, and the squad have responded this week by doing away with their regular "team bonding" drinking sessions.
Team manager Derek Quinnell told reporters at a press conference in Hong Kong: "The players have put a ban on themselves really.
"We went out last night for an hour with (representatives from Danish brewers) Carlsberg and I think they were under the impression that a few pints would be sunk, but about 90 per cent of the players were drinking coke.
"They know that last weekend wasn't good enough and it was a kick up the backside for us. They are more focused this week and the players know that if they don't look after their bodies in this sort of heat, they've got a problem coming. Fair play to them, they have reacted well to that."
The Barbarians trailed 40-0 to England before getting on the scoreboard with tries from Elliott Daly and Schalk Brits, and they know more is expected against Warren Gatland's men.
Young said: "We are not going to shy away from the fact that we all felt let down afterwards. We didn't play anything like we expected and we know we are going to have to be a lot better.
"The players realised themselves that they have to step things up this week, and preparation and training has been spot on.
"We have been concentrating on getting the basics right and earning the right to play rather than just going out there to chuck the ball around."
Italy's Sergio Parisse will captain the side on Saturday and told the Telegraph: "I played two years ago for the Baa-Baas and it is a big honour to be back again.
"For any player, especially from Italy, it is a great opportunity and I know we have enough talent and skill among this group of players to put the Lions under pressure."
The Stade Francais star, an inspirational leader for the Azzurri, will line up at number eight in a much-changed side.
He will be flanked in the back row by Northampton's Samu Manoa and Wasps' Sam Jones, one of three uncapped players along with club-mate Daly - who switches from full-back to outside centre - and incoming number 15 Jared Payne of Ulster.
Wales' Paul James and Italy's Martin Castrogiovanni are the props either side of Brits, who steps up from the bench, while Wasps' South Africa lock Marco Wentzel is the only forward retained in the starting line-up and is joined in the second row by Australia's Dean Mumm.
Welsh pair James Hook and Dwayne Peel are replaced by Nick Evans and Dimitri Yachvili in the half-back positions while Joe Rokocoko joins fellow All Black Casey Laulala and United States international Takudzwa Ngwenya in a three-quarter line completed by Daly.
Hong Kong wing Rowan Varty was added to the matchday squad after the initial announcement due to a groin strain suffered by former England centre Mike Tindall, who will be assessed on the morning of the game.
Saturday's clash is the opening game of the Lions' tour before they proceed to Australia for three Tests and another six fixtures against Australian state sides and a combined New South Wales-Queensland XV.
Barbarians team: J Payne (Ulster); J Rokocoko (Bayonne & New Zealand), E Daly (Wasps), C Laulala (Munster & New Zealand), T Ngwenya (Biarritz & USA); N Evans (Harlequins & New Zealand), D Yachvili (Biarritz & France); P James (Bath & Wales), S Brits (Saracens & South Africa), M Castrogiovanni (Leicester & Italy), M Wentzel (Wasps & South Africa), D Mumm (Exeter & Australia), S Manoa (Northampton & USA), S Jones (London Wasps), S Parisse (Stade Francais & Italy, captain).
Replacements: L Ghiraldini (Benetton Treviso & Italy), D Jones (Ospreys & Wales), A Lo Cicero (Racing Metro & Italy), J Hamilton (Gloucester & Scotland), I Harinordoquy (Biarritz & France), K Fotuali'i (Ospreys & Samoa), J Hook (Perpignan & Wales), M Tindall (Gloucester & England) or Rowan Varty (DeA Tigers & Hong Kong).