Ballinderry were forced to withstand a second-half onslaught before overcoming 14-man Kingdom Kerry Gaels at Ruislip.
The Ulster champions looked home and hosed at the interval, leading 1-5 to 0-1, and had extended their advantage to 11 points by the midway point of the second period.
But Kingdom Kerry Gaels produced a gutsy late rally, scoring 2-3 in a frantic 11-minute period to leave a goal between the sides.
Ballinderry managed to hold on, hitting two late points to secure victory, but manager Martin McKinless admits they have a lot of work to do ahead of their All-Ireland semi-final date with St Vincent's in February.
"We thought we were in cruise control at half-time," he said. "We lost possession, carried the ball into the tackle instead of spreading it. We didn't create the space we normally do but conditions out there were very poor.
"At the end of the day we're delighted to be in the position we're in. Today was just about getting over the line. We knew coming here that the facilities were poor. We were taken out of our comfort zone."
Such a close contest never looked likely during the first half, where Ballinderry quickly gained the ascendancy.
The home side were a shambles in that opening period, with London forward Lloyd Colfer fluffing three close-range frees as their strategy of piling bodies into midfield left them short of options up front.
That profligacy was punished in the ninth minute when Conor Devlin netted his first of two goals, but Ballinderry were guilty of some wayward shooting themselves as they racked up seven first-half wides.
Two further goals chances went abegging too. Some last-gasp defending denied Michael McIver, while KKG goalkeeper Shaun Howard produced a fine save to deny Conleith Gilligan late in the half.
KKG were reduced to 14 men on 25 minutes when full-back Peadar Stack received a second yellow card, and the match looked over as a contest when Devlin teed up Daniel McKinless for a fisted goal early in the second half.
McKinless returned the favour on 42 minutes by passing across goal for Devlin to finish, but the home side's response was immediate, Stephen Browne firing home from close range after Michael Conlan could only parry Caoimhin Carty's shot.
The Kingdom hit three points in as many minutes to cut the gap to six, and it was a one-score game when Kyle Holland slotted a 54th-minute penalty after Ciaran McCallion -- an All-Ireland minor winner with Derry in 2002 -- was dragged down inside the area by Conor Nevin.
Nevin redeemed himself two minutes later by kicking an insurance point, but KKG manager Noel Dunning hopes that his side's second-half performance will put a stop to criticism regarding the participation of London clubs in the All-Ireland series. "What's cost based on the development of the game?" asked the former London manager.
"It's not the same team that comes over every year. Croke Park does more than enough to finance people coming over, in my opinion.
"We get it going the other way and are able to work within that budget. That's the way it is.
"People know at the start of the year that if they win their provincial title, you're likely facing a trip to London.
"If they decide not to plan for that, that's their problem.
"This thing about the London champions not being deserving of an All-Ireland quarter-final spot... I hope we put that to bed today with our performance.
"I'm sure at half-time a lot of people were saying that this was a waste of time. We fed off that for the second half. I think we shut those people up and hopefully that will stop the chirping, bleating and knocking of London football."
Scorers - Ballinderry: C Devlin 2-1 (1f), D McKinless 1-1, R Bell, C Gilligan (1f) 0-2 each, D McGuckin, C Nevin, F Ball 0-1 each. Kingdom Kerry Gaels: K Holland (1-0pen), S Browne 1-1 each, T O'Sullivan 0-2 (2fs), L Colfer (f), A Dillane, C McCallion 0-1 each.
Ballinderry -- M Conlan; R Scott, C Nevin, M McInver; R Wilson, G McKinless, D Lawn; Kevin McGuckin, J Conway; D McKinless, Kevin 'Moss' McGuckin, D McGuckin; C Devlin, R Bell, C Gilligan. Subs: C Wilkinson for Scott (17), D Conway for Wilson (ht), P Crozier for Lawn (36), F Bell for Gilligan (45), A Devlin for Kevin 'Moss' McGuckin (57).
Kingdom Kerry Gaels -- S Howard; P Kelly, P Stack, C O'Neill; C Carty, P Horkan, D McGreevy; A Daly, S Browne; A Dillane, K Holland, C McCallion; N O'Connell, L Colfer, C Deely. Subs: K Waldron for Daly (25), C Hands for O'Connell (ht), T O'Sullivan for Colfer (38), A Kenny for Holland (59), C Griffin for Dillane (60).
Ref -- C Lane (Cork)