2021 Estoril Open – Singles
Albert Ramos Viñolas defeated Cameron Norrie in the final, 4–6, 6–3, 7–6 to win the singles tennis title at the 2021 Estoril Open. It marked his third career ATP Tour singles title, all of which have been on clay. Norrie was aiming to win his first ATP Tour title in his second final. Stefanos Tsitsipas was the defending champion from when the tournament was last held in 2019, but did not return to compete. Seeds. The top four seeds received a bye into the second round.