Gloucester secured top spot and a home play-off as they muscled past Bath 8-6 in the Guinness Premiership at Kingsholm on Saturday.
But there were major injury concerns for watching England boss Martin Johnson as Gloucester centre Mike Tindall, Bath prop Matt Stevens and his front-row colleague Lee Mears all failed to last the distance of a punishing encounter.
Johnson and Rob Andrew are due to announce a 32-man squad for next month's New Zealand tour on Tuesday.
And they will be anxious for early fitness updates on a trio expected to start against the All Blacks in Auckland on June 7.
Despite Tindall's early departure, Gloucester kept their shape and discipline to book a home semi-final against reigning champions Leicester tomorrow week.
Wing James Simpson-Daniel's 34th-minute try shaded an intense encounter, preserving Gloucester's place at the Premiership summit and consigning Bath to second spot.
Bath now face a daunting semi-final away to Wasps after a losing bonus point was not enough to preserve second spot.
Gloucester-bound Olly Barkley booted two penalties for the visitors, but a scoreless second period reflected how two committed sides cancelled each other out.
England wing Lesley Vainikolo returned for Gloucester after recovering from a hamstring strain. His Test colleague Iain Balshaw moved to full-back instead of Olly Morgan, with number eight Gareth Delve handed a start against his former club.
Wing Andrew Higgins, centre Tom Cheeseman and prop David Flatman represented a trio of Bath changes following their 66-21 drubbing of Saracens last Saturday, while Barkley lined up against the team he will join next season.
And both sides showcased their attacking instincts during a lively opening quarter.
Balshaw's pace stretched the Bath defence before his inside pass almost sent Tindall clear, then wing Matt Banahan sprinted clear and was hauled down by a superb last-ditch Balshaw tackle.
Tindall though, a leading contender to captain England in New Zealand, limped off in the seventeenth minute and was replaced by Willie Walker, before Lamb rifled over a 35-metre penalty to edge Gloucester ahead.
Territorially, Bath were in complete control, but they encountered a Gloucester defence ferociously committed to knocking them back in the tackle.
Bath looked to have finally broken through in the 25th minute when Stevens rampaged clear, but a stunning Simpson-Daniel tackle denied him five metres from the line.
Stevens was forced off injured as a result of Simpson-Daniel's defensive brilliance, and although Barkley quickly struck an equalising penalty, Gloucester moved ahead before the break.
Slick handling left Bath short of defensive numbers, and Simpson-Daniel did not require a second invitation to cut back inside for a clever try.
Lamb could not convert, and despite Barkley landing a second penalty to cut the deficit, Gloucester trooped off two points ahead after a high-octane half played in stamina-sapping conditions.
There was not let-up in terms of intensity or commitment after the break, yet scoring opportunities were at a premium.
Gloucester thought they had done enough to seal the deal when Vainikolo stormed clear in space to send substitute Luke Narraway over, but referee Dave Pearson ruled a forward pass during the build-up.
Bath threw everything at their opponents during the frenzied closing stages, but they lacked a cutting edge and Gloucester comfortably held them out.
Pen: Barkley 2
Gloucester: 15 Iain Balshaw, 14 Lesley Vainikolo, 13 Mike Tindall, 12 Anthony Allen, 11 James Simpson-Daniel, 10 Ryan Lamb, 9 Rory Lawson, 8 Gareth Delve, 7 Akapusi Qera, 6 Alasdair Strokosch, 5 Alex Brown, 4 Marco Bortolami (c), 3 Carlos Nieto, 2 Andy Titterrell, 1 Nick Wood.
Replacements: 16 Olivier Azam, 17 Alasdair Dickinson, 18 Will James, 19 Luke Narraway, 20 Gareth Cooper, 21 Willie Walker, 22 Mark Foster.
Bath: 15 Joe Maddock, 14 Andrew Higgins, 13 Tom Cheesmen, 12 Olly Barkley, 11 Matt Banahan, 10 Butch James, 9 Michael Claassens, 8 Daniel Browne, 7 Michael Lipman, 6 Jonny Faamatuainu, 5 Danny Grewcock, 4 Steve Borthwick (c), 3 Matt Stevens, 2 Lee Mears, 1 David Flatman,
Replacements: 16 Pieter Dixon, 17 Duncan Bell, 18 Peter Short, 19 Chris Goodman, 20 Nick Walshe, 21 Shaun Berne, 22 Alex Crockett.
Referee: Dave Pearson
Touch judges: Peter Huckle, Stuart Terheege
Assessor: Ed Morrison
Television match official: Laurie Bryant, Graham Hughes