Barcelona were made to work for victory over Alaves on Sunday but late goals from Luis Suarez and Lionel Messi saw them equal a club record.
Ernesto Valverde's men remain 11 points clear at the summit and their streak of 21 games unbeaten represents Barcelona's best run from the start of a LaLiga season.
Pep Guardiola's 2009-10 title-winning side won 17 and drew four over the course of their streak, but Messi's exquisite free-kick means Vlaverde's vintage have 18 victories and three draws to their name.
21 - Barcelona have equaled their longest unbeaten start to a league campaign in their history (W18 D3); under Pep Guardiola in 2009/10 (W17 D4 L0). Unstoppable. pic.twitter.com/jrCVXGXuWD— OptaJose (@OptaJose) January 28, 2018
Messi is represented across the three best returns, with Tito Vilanova's Barca going 19 games without defeat from the outset in 2012-13.
The next entry on the list falls some way further back, with Terry Venables leading Barcelona to 15 games unbeaten in 1984-85.
Should Valverde's side avoid defeat in next weekend's derby at Espanyol, they will be out in front on their own, although their local rivals did win 1-0 Cornella-El Prat in the first leg of this month's Copa del Rey quarter-final.