Iga Swiatek and Carlos Alcaraz won in straight sets to retain their titles in Stuttgart and Barcelona respectively.
Polish world number one Iga Swiatek beat world number two Aryna Sabalenka of Belarus 6-3 6-4 in a repeat of last year’s final.
In Spain, Alcaraz breezed past Stefanos Tsitsipas of Greece 6-3 6-4 to win the tournament without dropping a set.
It was a third title of the season for the 19-year-old Spaniard, following wins in Buenos Aires and Indian Wells.
Both Swiatek and Alcaraz have been suffering from injury in recent weeks but have returned to fitness and form as they build up to the French Open at Roland Garros next month, where the Pole will be defending her title.
Swiatek was playing her first tournament since recovering from a rib injury that forced her to miss the Billie Jean King Cup qualifiers and Miami Open.
She is the first player to win back-to-back Stuttgart titles since Angelique Kerber in 2015 and 2016, with Sabalenka suffering her third successive defeat in the final.
It was the first time a women’s world number one had faced the number two on clay since Serena Williams beat Maria Sharapova in the 2013 French Open final.
Alcaraz, meanwhile, appeared so show no ill-effects from the hand and back problems that forced him to miss the Monte Carlo Masters last week.
With 14-time French Open champion Rafael Nadal out since January with a hip injury and world number one Novak Djokovic struggling with an elbow problem, Alcaraz will be among the key contenders when the tournament in Paris begins on 28 May.
In the men’s doubles final in Barcelona, Great Britain’s Neal Skupski and Dutch partner Wesley Koolhof were beaten by Argentine pair Maximo Gonzalez and Andres Molteni.
Gonzalez and Molteni won 4-6 7-6 (10-8) 10-4 to claim their third title of the year after victories in Cordoba and Rio de Janeiro.