Atletico Nacional were unable to close out the Copa Libertadores group stage with a 100 per cent record after being held to a goalless draw by Huracan.
Group 4 winners Nacional had already qualified for the round-of-16 thanks to five consecutive wins.
But the Colombian giants could not make it a perfect six from six, though they did emerge from the group without conceding a goal after the draw at Estadio Atanasio Girardot.
Huracan joined them in the knockout phase after Penarol came from behind to prevail 4-3 at home to Sporting Cristal.
A quick-fire Alberto Rodriguez brace had Sporting 2-0 up inside 24 minutes, until Luis Aguiar hit back on the half-hour mark, though Irven Avila restored the visiting team's two-goal lead seven minutes later.
However, that is as good as it got for Sporting after Hernan Novick restored parity with nine minutes remaining and Nicolas Albarracin completed the comeback in the 85th minute.
Meanwhile, Toluca closed out Group 6 as winners, despite losing 1-0 at second-placed Gremio.
The other match in the group saw San Lorenzo and LDU Quito play out a 1-1 draw.