Leicester kept alive their hopes of a Heineken Cup quarter-final place, by grinding French aristocrats Toulouse into the Welford Road mud.
Tigers fly-half Andy Goode's revered kicking game drove the hosts to victory.
Goode slotted three penalties, but his tactical authority on a miserable east midlands afternoon kept Leicester on course.
All Blacks World Cup centre Aaron Mauger experienced a muted introduction to Leicester colours - he was substituted 20 minutes from time - yet Tigers did just enough, courtesy of wing Ollie Smith's 12th-minute try and an influential display by number eight Jordan Crane.
Toulouse fly-half Valentin Courrent booted two penalties and dropped a goal, while the three-time European champions arguably created more clear-cut chances.
Leicester, though, stayed in Pool Six contention for tomorrow week's return fixture at Stade Ernest Wallon - on a day when their sheer cussedness and wet-weather skills again served them well.
The Tigers forwards, well-marshalled by captain Martin Corry, relished a ferocious battle up front; yet Toulouse's losing bonus point kept them top of Pool Six and means Leicester still have it all to do.
The clubs, who boasted five European titles between them, were locked 2-2 on previous Heineken Cup meetings - and Tigers knew they could not afford to fall behind in the overall series.
England World Cup forwards Ben Kay (hamstring) and Lewis Moody (ankle) missed the Anglo-French showdown, but Mauger's debut - just 11 days after he arrived from New Zealand - attracted most attention.
Mauger's former All Blacks colleague Byron Kelleher edged the Toulouse scrum-half vote above Jean Baptiste-Elissalde, and the visitors knew that victory would tighten their grip on the pool.
Leicester struggled to cope with Toulouse's early ambition as the French side looked to move possession wide, despite difficult conditions.
Courrent kicked them into a deserved eighth-minute lead - with Leicester finding it difficult to contain Toulouse's off-loading game, and only Goode's prodigious tactical boot kept them in touch.
Goode's accuracy and distance proved a problem for Toulouse, but the visitors fell behind purely because of their own attacking adventure falling flat.
Full-back Clement Poitrenaud tried to run possession from deep. But his optimism fell flat as Leicester scooped up loose possession, and Smith sprinted clear for an opportunist try.
Goode's opening penalty 15 minutes later hoisted Leicester 8-3 clear, but a Courrent drop-goal narrowed the gap by half-time.
Tigers lost injured scrum-half Frank Murphy at the break - Ben Youngs replaced him - and Toulouse moved ahead for the second time when Courrent landed a 43rd-minute penalty.
It was a valiant performance by Toulouse in alien conditions for them, but they fell behind when Goode found his range on 55 minutes to edge Leicester 11-9 ahead.
Toulouse continued to make a real fist of the contest, yet another indiscretion saw Goode complete his penalty hat-trick nine minutes from time.
There seemed no way back for the visitors, despite the unflinching efforts of French World Cup flankers Yannick Nyanga and Thierry Dusautoir.
Leicester had enough left in the tank to close matters out, but conditions are unlikely to favour them in such a fashion next weekend.
Toulouse could even have snatched it at the death, but wing Cedric Heymans' surge for the line was halted by a forward pass.
With only one team likely to progress from the group, Leicester's fate might not be decided until their final game against Welford Road visitors Leinster on the third weekend of January.
But Goode's display ensured their hopes of a third European title will extend beyond Christmas.