The Blues' Super Rugby season has suffered a serious setback with 43-5 loss to the Lions in soggy Johannesburg.
A listless performance from the Blues was their worst of the season, conceding seven tries to the rampant South Africans.
Blues reserve flanker Kara Pryor scored their try in the dying minutes.
Lions centre Lionel Mapoe bagged a second-half hat-trick after his team led 19-0 at halftime.
His team defied heavy rain throughout the contest to play with verve, guided superbly by first five-eighth Elton Jantjes.
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The lopsided win, easily their biggest over the Blues, was the Lions' seventh from 10 games.
It lifts them to the top of the South African group and six points clear of nearest rivals the Sharks in the Africa 2 conference.
The Blues had won their three previous games, but are now virtually out of contention to win the powerhouse New Zealand conference.
They sit 11 points behind the fourth-placed Hurricanes after suffering a fourth loss of the season.
Their start on Saturday mirrored the cold conditions, conceding a try to rampaging Lions captain Warren Whitely inside the first minute.
Jantjes then took control, using deft attacking kicks to set up winger Courtnall Skosan and second five-eighth Rohan Janse van Rensburg.
Mapoe's three tries were all impressive team efforts as the Blues struggled to halt the Lions' relentless march over the advantage line.
Flanker Warwick Tecklenburg scored their other try from the lineout drive before Pryor's late consolation.
