London Irish remain top of the Aviva Premiership after posting a fortunate 12-9 win over a battling Exeter side.
The leaders were indebted to Ryan Lamb for his two penalty goals in the final 10 minutes, as Exeter were more than a match for their lofty opponents for much of the contest.
The opening exchanges were evenly contested before Exeter built up the first period of sustained pressure in the visitors' 22.
Irish were penalised but Gareth Steenson surprisingly missed an easy penalty chance.
Exeter kept up the pressure when centre Phil Dollman burst past Ryan Lamb's weak tackling effort and the Irish line looked in danger but the Chiefs were penalised to allow the Exiles to clear.
It was therefore against the run of play when Irish took the lead after 16 minutes when Lamb kicked a 45-metre penalty goal.
However Exeter continued with some ferocious tackling which prevented the visitors from building up momentum in their play.
In addition the Irish scrum was frequently penalised by referee Wayne Barnes, conceding a number of penalties, one of which Steenson kicked to bring Exeter level after 22 minutes.
Irish attempted to bring some continuity to their play and their dangerman, Seilala Mapusua, threatened with a couple of trademark runs but too often their handling let them down.
The scrummage was also becoming more and more of a problem for the visitors as their opponents seemed to be stronger in that area.
Three minutes before the interval Exeter won a line-out in the opposition 22 and drove forward. Again the Irish were penalised and Steenson kicked the goal.
From the restart back came the Irish and when Exeter lost a line-out in their own 22, the home side were then penalised and Lamb kicked the goal with the last kick of the half to make it 6-6 at the interval. Irish were probably a shade fortunate to be level.
Another careless pass from Lamb was intercepted by Tom Johnson which allowed the Chiefs early pressure in the second half, and there was a further setback for Irish when Delon Armitage was yellow-carded for a high tackle on Andrew Higgins after 47 minutes.
Exeter continued to have the better of play in terms of possession and territory but too often they lost line-out ball which prevented them from putting Irish under more sustained pressure.
Armitage returned with no damage done to the scoreline, but despite having their best period of the match the visitors were firmly held in check by a huge defensive effort from the home side.
Exeter were dealt a blow after 61 minutes when they lost the influential Steenson to a leg injury, but that was immediately offset by his replacement, Ryan Davis, giving his side the lead by firing over a 30-metre drop goal.
The visitors then upped their game and had 10 minutes of pressure which culminated in Lamb kicking a 22-metre penalty to bring his side level with nine minutes remaining.
Four minutes later Exeter were penalised at a ruck 40 metres out and once again Lamb made no mistake with a match-winning kick.
Pen: Steenson 2
For London Irish:
Pen: Lamb 4
Exeter Chiefs: 15 Luke Arscott, 14 Andrew Higgins, 13 Phil Dollman, 12 Bryan Rennie, 11 Mark Foster, 10 Gareth Steenson, 9 Haydn Thomas, 8 Richard Baxter, 7 James Scaysbrook, 6 Tom Johnson, 5 James Hanks, 4 Tom Hayes (c), 3 Chris Budgen, 2 Neil Clark, 1 Brett Sturgess.
Replacements: 16 Chris Whitehead, 17 Ben Moon, 18 Hoani Tui, 19 Peter Kimlin, 20 Chad Slade, 21 Garrick Cowley, 22 Ryan Davis, 23 Sireli Naqelevuki.
London Irish: 15 Delon Armitage, 14 Topsy Ojo, 13 Seilala Mapusua, 12 Daniel Bowden, 11, Sailosi Tagicakibau, 10 Ryan Lamb, 9 Paul Hodgson, 8 George Stowers 7 Chris Hala'ufia, 6 Kieran Roche, 5 Bob Casey, 4 Nick Kennedy, 3 Alex Corbisiero, 2 David Paice, 1 Clarke Dermody (c).
Replacements: 16 James Buckland, 17 Dan Murphy, 18 Faan Rautenbach, 19 Kieran Low, 20 Matt Garvey, 21 Jonathan Joseph, 22 Chris Malone, 23 Darren Allinson
Referee: Wayne Barnes