The beginning of the 2019–20 season saw more consistent results. After the first five games of the season, the "Lions" sat at the top of the table, their best start in 26 years. That form could not be maintained, and by the halfway point they had slipped to mid-table after several draws. However, in the Copa del Rey, they survived two penalty shootouts against second-tier opponents and then defeated Barcelona to reach the semi-finals. The club then defeated Granada CF in the semi-final on away goals to meet local rivals Real Sociedad in the final – which was then postponed due to the COVID-19 pandemic in Spain, both clubs happy to delay in the hope of supporters being able to attend the historic Basque derby occasion. This did not come to pass, and the final was eventually played in an empty stadium in 3 April 2021, Real Sociedad emerging winners by a 1–0 scoreline. By that time, Aduriz had finally retired from playing, Garitano had been replaced as coach by Marcelino, and the 2020–21 Supercopa de España originally intended to follow the delayed cup final was contested, Athletic defeating Real Madrid then Barcelona to claim the trophy. They also defeated Levante in the semi-final of the 2020–21 Copa del Rey to reach the final on 17 April 2021, against Barcelona once again, making them the only team to have the privilege of taking part in the Cup final twice in as many weeks.