London Irish and Wasps scored five tries each as they battled to a 40-40 draw at Madejski Stadium on Saturday.
The Exiles went into the break 22-18 ahead following tries from Andrew Fenby, Alex Lewington and Chris Noakes, as well as seven points from the boot of Shane Geraghty.
Dai Young's men responded through Guy Thompson and Sailosi Tagicakibau touchdowns and two Andy Goode penalties.
Tagicakibau and Rob Miller went over in the second period to give the Coventry-based outfit the lead for the first time before James Short's effort reduced that deficit to one point.
In the end the teams had to settle for a draw as Andy Short and James Haskell traded late tries, while Geraghty added a three-pointer.
Despite going into the encounter in pole position for sixth place, Wasps needed two points to confirm their position in next season's Champions Cup.
In the end it wasn't to matter as Sale Sharks, their competitor for sixth, went down 44-16 to Exeter Chiefs, but they were still given a scare by Irish.
Fenby got the hosts off to the perfect start with a try but Thompson responded for Young's side almost immediately to level matters.
However, the Exiles controlled most of the first half and took a 19-12 advantage as Lewington and Noakes went over, although Tagicakibau's touchdown kept the away team in contention.
Goode and Geraghty then traded three-pointers before the visiting pivot reduced the deficit to four points at the interval from the tee.
Irish's stand-off regained the hosts' seven-point buffer but Tagicakibau's second try and Miller's effort took Wasps in front for the first time in the encounter.
Goode's penalty opened that lead out to eight points but back came Glenn Delaney's men as James Short crossed the whitewash and Geraghty kicked a three-pointer.
Haskell powered over to seemingly secure the win for the visitors, but a late score from Andy Short meant that the teams were forced to settle for a share of the spoils.
For London Irish:
Tries: Fenby, Lewington, Noakes, J Short, A Short
Cons: Geraghty 3
Pens: Geraghty 3
Tries: Thompson, Tagicakibau 2, Miller, Haskell
Cons: Goode 3
Pens: Goode 3
London Irish: 15 Andrew Fenby, 14 Alex Lewington, 13 Eoin Griffin, 12 Shane Geraghty (c), 11 James Short, 10 Chris Noakes, 9 Darren Allison, 8 Tom Guest, 7 Blair Cowan, 6 Luke Narraway, 5 Jebb Sinclair, 4 Dan Leo, 3 Richard Palframan, 2 David Paice, 1 Tom Court.
Replacements: 16 Jimmy Stevens, 17 Tom Smallbone, 18 Halani Aulika, 19 Ollie Curry, 20 Ofisa Treviranus, 21 Callum Watson, 22 Eamonn Sheridan, 23 Andrew Short.
Wasps: 15 Andrea Masi, 14 Christian Wade, 13 Elliot Daly, 12 Alapati Leiua, 11 Sailosi Tagicakibau, 10 Andy Goode, 9 Charlie Davies,8 Guy Thompson, 7 James Haskell (c), 6 Ashley Johnson, 5 James Gaskell, 4 Joe Launchbury, 3 Lorenzo Cittadini, 2 Tom Lindsay, 1 Matt Mullan.
Replacements: 16 Simon McIntyre, 17 Will Taylor, 18 Kearnan Myall, 19 Sam Jones, 20 Thomas Young, 21 Piri Weepu, 22 Alex Lozowski, 23 Rob Miller.
Venue: Madejski Stadium
Referee: JP Doyle
Assistant Referees: Ian Tempest, Andrew Pearce
TMO: David Grashoff