He notably played in the Primeira Liga where he made a total of 279 matches and 97 goals during ten seasons, mainly with Benfica where he spent five of those years, winning three major titles.
Arguably his greatest moment with the Lisbon side came on 6 November 1991, in the last round prior to the group stage of the season's European Cup: against Arsenal, at Highbury Park, he assisted once and netted twice in a 3–1 win (4–2 aggregate success).
Subsequently, Isaías moved to England with Coventry City for £500.000, signing a two-year contract and becoming the first Brazilian to ever play in the Premier League.
[1][5] He featured in just 14 competitive matches for the Sky Blues over a period of two seasons, due to differences with manager Gordon Strachan and his refusal to cancel his contract after no compensation would be paid.
[1] He retired in his country at almost 40 with Cabofriense, then appeared in a few games with the Portuguese beach soccer team courtesy of his previously obtained citizenship.