The Basque side had drawn their two previous fixtures 0-0 but with Fernando Llorente back fit they looked a much more potent attacking force, even though the Spain striker didn't get on the scoresheet himself.
Bielsa told Efe: "The game against Albacete was an exception because the level that we reached in that game didn't correspond to what we had done in the previous matches.
"The attack was effective and varied in their play and we had many chances that were shared out amongst our offensive players."
Llorente should start again against Levante after being brought off with 25 minutes remaining on Thursday as a precaution, whilst Fernando Amorebieta could also return to the starting line-up after he returned to full training this week.
Levante also progressed to the last eight of the cup this week and are seven points clear of Athletic in fourth place. However, coach Juan Ignacio Martinez believes the club must invest this month if they are to have any chance of maintaining their current position.
He told Marca: "The sporting director is working hard on this because we need to bring in players. We have already lost two squad members and we can't allow the squad to be weakened.
"At the moment there is no one in the pipeline but what we want is always good, nice and cheap players who want to come here and compete."
Ahead of this weekend's fixture Martinez underlined his own point by stressing Athletic's strength in depth.
"They will cause us a lot of problems because they have many alternatives. Since the arrival of Bielsa they are playing a different type of football to that that they have historically played and now they play a lot more with the ball."
Martinez will at least have the boost of having Javi Venta and Nano back after they missed last weekend's 0-0 draw with Mallorca due to suspension, but winger Valdo remains a doubt.