A two-try burst before half-time saw the Blues to a tense win over Glasgow.
Blues (15) 24
Tries: Tuilagi, Schubert
Pens: Thomas (4)
Glasgow (13) 19
Pens: Howarth (4)
The Cardiff side had a dreadful start at the Arms Park, letting Andrew Wilson in for a soft 10th-minute try.
But Freddie Tuilagi and Kort Schubert went in for tries within two minutes of each other to wrest back the advantage for the home side.
Calvin Howarth's 14 points kept Glasgow close, but Lee Thomas matched his tally and when Eric Milligan was sin-binned towards the end the result was sealed.
The Blues were defending a 100% league record at the Arms Park this season, but an early Howarth penalty for Glasgow was followed by a gift of a try.
Flanker Wilson picked up at a ruck in midfield 35m from the Blues' line and simply ran through a gaping hole in the
defence for a converted score.
Thomas and Howarth exchanged penalties, before wing Craig Morgan ignited the home team with a run to the corner.
He was just bundled out, but from the resulting line out captain Craig Quinnell drove forward well and released to the backs,
where Morgan sent Tuilagi over for a try.
Two minutes later scrum-half Richard Smith broke superbly from deep in his own half and made it to the Glasgow 22.
The ball was recycled well, and with the Scottish defence in disarray simple passing sent No 8 Schubert in for a try
that gave the Blues a 15-13 half-time lead.
The Blues' fragile confidence showed as they struggled to press home the advantage in a scrappy second half, as Thomas and
Howarth shared two penalties apiece.
But on 76 minutes replacement Glasgow prop Milligan was sin-binned for an offence at a ruck.
Thomas' fourth penalty took the Blues five points clear, a lead they held until the end.
"We worked hard during the week, and any win is a good one for us at the moment," said Blues captain Quinnell.
"Our line-out and scrum went well so we had a platform, and Richard Smith's break was tremendous to give us one of our best tries of the season.
"We've now got to get ready for a real tough test in Ulster next week."
Blues: C Morgan; D Dewdney, S James, L Thomas, F Tuilagi; N Macleod, R Smith; J Yapp, R Thomas, B Evans, C Quinnell (capt), R Sidoli, N Budgett, R Sowden-Taylor, K Schubert.
Replacements: A Lewis, M Jones, G Williams, D Jones, N Thomas, R Powell, M Nuthall.
Glasgow: Rory Lamont; Rory Kerr, Andy Craig, Gareth Maclure, Kenny Logan (capt); Calvin Howarth, Sam Pinder; Andrew Kelly, Scott Lawson, Euan Murray, Andy Hall, Dan Turner, Steve Swindall, Andrew Wilson, John Beattie.
Replacements: Fergus Thomson, Eric Milligan, Joe Beardshaw, John Barclay, Graeme Beveridge, Colin Gregor, Colin Shaw.
Referee: George Clancy (Ireland)