Manuel Pellegrini's side sit in third spot in the Liga table and the Chilean coach said he was delighted with the performance and the result.
"The result is a fair reflection of the match and a good outcome in a tough San Mames atmosphere, against a very difficult rival in Athletic," he told AS.com
The 59-year-old was also pleased to see no lasting effects following their Champions League win over Zenit Saint Petersburg on Tuesday.
"I do not think fatigue was noticeable from Tuesday's game. We moved the ball well and ran a lot with it," he added.
The Chilean coach also revealed that an injury to Jeremy Toulalan is likely to sideline the midfielder for two to three weeks.