Complex sentence: On 26 August, Benfica took part in the draw for the group stage of the 2005--06 UEFA Champions League; their first in the new century because they failed to qualify in the past two seasons.
Split into simpler sentences: On 26 August, Benfica took part in the draw for the group stage of the 2005--06 UEFA Champions League. It was their first in the new century, as they failed to qualify in the past two seasons.