Scottish Premier League clubs are counting the cost of the Old Firm's poor form in European competition, reports BBC Sport. Revenue fell by £31m to £168m in 2008/09 after Celtic and Rangers bowed out of the Champions League, according to a financial report by Deloitte.
Operating profits of £6m in the previous season gave way to losses of £11m and a small reduction in wages.
However, the report said the SPL acted "decisively" in July 2009 to strike a new TV broadcasting deal.
SPL clubs reduced wages by £4m from £115m to £111m in 2008/09, but it was less than the £31m fall in revenue over the same period.
During that season, Celtic finished bottom of Champions League Group E following a disappointing campaign against Manchester United, Villarreal and Aalborg.
Old Firm rivals Rangers failed to make the group stages after losing to FBK Kaunas in the second qualifying round.
"The total revenues hinge on the on-pitch performance of the two Old Firm clubs, who accounted for two thirds (£112m) of SPL clubs' revenue," said Deloitte's Dan Jones.
"Celtic and Rangers' earlier exits from European competition in 2008/09 triggered decreases in matchday (£14m) and broadcast revenues (£16m)."
The SPL agreed a £65m five-year deal with Sky and ESPN to screen 60 live matches each season.
And Jones added: "Looking more widely, the SPL acted decisively in July 2009, after the collapse of Setanta, by awarding BSkyB and ESPN live rights to SPL games from 2009/10, thereby providing certainty and stability for its clubs.
"The reported value of £13m per season for live rights is only slightly below 2008/09 levels which, given the current economic climate, may be seen as a qualified success."
Commercial revenue was £50m (30%), but averaged less than £2m per club for the non Old Firm clubs.
At £35m, broadcast revenue (including UEFA distributions) is the smallest income stream and was less than the average received by each English Premier League club in 2008/09 (£48m).
The report highlighted the financial importance of Scottish clubs enjoying extended runs in Europe, citing Celtic's position in the Top 20 of Deloitte's football money league in 2008.
"The SPL clubs' on-pitch performance in Europe this season, when taken in conjunction with the new SPL broadcast deals, means that we expect SPL revenues to be similar in 2009/10 to those in 2008/09," Deloitte's Alex Byars added.