Athletic Club are one of just three teams never to have been relegated from LaLiga, along with Barcelona and Real Madrid.
Just as Real Sociedad were contemplating opening a three-point advantage over Real Madrid and Sevilla at the top, Athletic Bilbao levelled in stoppage time
Bilbao jumped into sixth place with the victory, just ahead of Barcelona, before the rest of the round this weekend.
Atlético Madrid try to end a two-game winless streak when they visit struggling Getafe in LaLiga.
LaLiga: Joao Felix sent off as Athletic Bilbao hold Atletico Madrid; Radamel Falcao nets in Rayo debut
LaLiga's reigning champions have now drawn two and won three of their opening five games while Athletic continue their impressive start under Marcelino Garcia Toral, whose side also drew with Barcelona last month.
Manchester City have scored at least five goals in each of their last four home games in all competitions. Next in the firing line at Etihad Stadium is Southampton
Inaki William’s first-half goal helped Athletic Bilbao win 1-0 at Celta Vigo, the first victory of the season for the Basque Country club.
Depay found the net with a fine left-foot half-volley 15 minutes from time in the Basque Country for his first goal in LaLiga since moving to Barcelona from Lyon.
LaLiga: Luis Suarez's dramatic late winner for Atletico Madrid takes title race to last day; Eibar relegated
Atletico's players and substitutes piled onto Suarez in the corner and at full-time, some of their players dropped to their knees, not with ecstasy, but relief, the title now just one win away.
According to media, Zidane, who has a contract until 2022, informed his squad a week ago that he was going to leave when the season ends next week.
Bayern, and Martinez, are on the brink of winning a ninth straight league title this Saturday.
Williams' first goal since February snatched a 1-0 win for Athletic and leaves Sevilla six points adrift of leaders Atletico Madrid, with four games left to play.
Losing to Athletic Bilbao means Atletico Madrid have won only six of their last 14 league games, with the momentum gained from consecutive wins over Eibar and Huesca proving short-lived.
Copa del Rey: Lionel Messi scores twice as Barcelona beat Athletic Bilbao to win 31st domestic Cup title
The cup was won and lost in a whirlwind 12 minutes in Seville, which saw Barca score four times to clinch an emphatic 4-0 victory, with Messi at his devastating best.
Victory in Seville this weekend would be the 31st time Barca have won the competition while Athletic are going for their 24th success
For Barca, losing to Athletic would be the kind of upset that could derail their LaLiga title challenge and undermine the progress made this season by Ronald Koeman, whose future remains uncertain.
The absence of Robert Lewandowski has left Bayern with a huge hole in attack, compounded by the unavailability of Serge Gnabry, who is isolating after contracting Covid-19.
Sociedad, who are based in San Sebastián, had only won the Copa del Rey twice previously in its history, in 1909 and in 1987, their last major trophy.
Leicester are chasing a double over the leaders after a stunning 5-2 win at the Etihad Stadium in September. Former City striker Kelechi Iheanacho is in fine form after scoring seven goals in his last four games for Leicester.
La Real will face bitter rivals Bilbao on Saturday in the postponed final from last season, which has been put off as long as possible in the hope that fans could attend.