Girona underlined their La Liga title credentials with a famous victory at Barcelona to move top of the table.
Goals from Artem Dovbyk, Miguel Gutierrez, Valery Fernandez and Cristhian Stuani gave the visitors a deserved first ever league win over their Catalan rivals.
The result sees Girona open up a two-point gap to Real Madrid.
Michel’s side are also seven clear of third-placed Atletico Madrid and Barca, who are fourth.
Girona’s rise to the top may have taken many by surprise but on this evidence they have the quality to stay the course.
Ukraine forward Dovbyk’s eighth goal of the campaign set them on their way in the 12th minute and came after he was expertly teed up by his international team-mate Viktor Tsyhankov, who beat the home side’s offside trap to escape down the right channel.
And while Lewandowski headed in an equaliser from Raphinha’s corner to draw Xavi’s side level seven minutes later, the visitors always carried a considerable threat on the counter.
Spain Under-21 left-back Gutierrez restored their lead with a surging run and left-foot finish into the left corner five minutes before the break.
German midfielder Gundogan briefly raised hopes of a home fightback in added time, but they were quickly extinguished by Stuani.
The Uruguay forward tapped in Girona’s fourth at the back post to cap a special night for the club, who have never finished higher than 10th and are only in their fourth season in La Liga.