The midfielder converted from the spot in the 59th minute after Jeremiah St Juste was penalised for handball. The goal proved enough to secure another three points for Manuel Pellegrini's team, who had already beaten Lille and Porto in their opening fixtures.
Speaking after the match, Isco emphasised the importance of the result and the collective effort required to secure it.
“It is an immense pleasure. We are all enjoying it, on the pitch and in the stands. I think it is something very important for us to keep growing. The results are helping,” he said.
The midfielder was particularly pleased with Betis' opening spell, believing the team had produced some of their best football of the season without fully capitalising on their opportunities.
“The first 35 minutes were among the best of the season. It was a shame that it was not reflected on the scoreboard, but this is football and it is difficult. The opponents are very good,” Isco explained.
Betis eventually secured the points after facing a more difficult second half, when Feyenoord enjoyed greater possession and attempted to find an equaliser.
“We got the three points in the second half, when we suffered more than in the first, but we suffered together,” he added.
Isco also acknowledged the quality of the Dutch opposition, highlighting their technical ability and position at the top of their domestic league. The Spanish side's ability to overcome that challenge left him proud of their performance.
“Happy to get the three points. Nine out of nine, it sounds simple when you say it, but I am proud of the whole team,” he said.
The victory strengthened Betis' hopes of finishing among the top eight in the league phase, which would provide a direct route into the Champions League knockout rounds.
Isco insisted that maintaining their mentality would be essential if they were to sustain their progress.
“We have to continue along this line, with the mentality of going out to win every match. That is the only way to grow. I see a team that is really switched on, and we have a very deep squad,” he said.
The midfielder also credited Pellegrini's trust in him for the responsibility of taking the penalty.
“The manager trusts me and, for now, I am scoring. I am happy to help the team with goals and hard work, always with enthusiasm and a desire for more,” Isco said.
Real Betis now have three wins from three in Europe, with Isco's latest contribution providing another decisive moment in their impressive campaign.