In 1973 Lorenzo went to Atlético Madrid, who went on to win the league title and lose the 1974 UEFA Champions League final to Bayern Munich. Back in Argentina, he coached recently promoted Unión de Santa Fe in 1975. The next year, he returned to Boca Juniors amid great pressure (rivals River Plate had just won back-to-back titles), and started one of the most successful periods in the history of the club. In his four-year tenure, Lorenzo and Boca took two local and three international titles, including the 1977 Intercontinental Cup (played in 1978).