#1 Barcelona lost for the first time in the 2017/18 season
Whilst not quite as remarkable as that of Skyblues, but another fine run was being scripted by Barcelona when they went 31 games unbeaten in all competitions since the start of the campaign, scoring in each of them as well.
Although they did go down to arch-rivals Real Madrid in both legs of the Spanish Supercup, the season is traditionally considered commencing with the first game of the league and going by the timeline since, the Blaugrana were undefeated till 17 January 2018.
That day, city rivals Espanyol sprung a surprise when they condemned their mightier neighbors to a shock 1-0 defeat in the quarter-finals of the Copa del Rey through a late goal by Melendo, as Barcelona ended up on the losing side of a game for the very first time in the campaign, bringing their amazing run of 31 undefeated matches to a close.