Rafael Nadal's chances of winning an 11th Barcelona Open title were markedly improved by the exits of Novak Djokovic and Kei Nishikori, although Dominic Thiem and Grigor Dimitrov progressed to round three.

World number one Nadal was tested by Spanish compatriot Roberto Carballes Baena, but – playing on the court named in his honour – he ultimately recorded a comfortable 6-4 6-4 win.

Nadal consequently extended the record for most consecutive sets won on clay to 38, and will next meet Guillermo Garcia-Lopez, who went through after Nishikori withdrew.

The Japanese – a losing finalist to Nadal in Monte Carlo last week – lost the first set 6-3 and later said he had "pain in three different parts of my body while warming up", the biggest of which was in his right calf.

Djokovic's disappointing 2018 continued in a 6-2 1-6 6-3 loss to Martin Klizan, the 12-time major winner having been a late addition to the draw following a round-three loss to Thiem in Monte Carlo.

There was better news for Thiem, a finalist in Barcelona a year ago, who saved set point in the opener en route to a 7-6 (10-8) 6-1 victory over Spanish wildcard Jaume Munar.

ATP Finals victor Grigor Dimitrov, who reached the Monte Carlo semi-finals, was in sublime form in his 6-2- 6-1 win over Gilles Simon.

Jozef Kovalik, Albert Ramos Vinolas, Pablo Carreno-Busta, Stefanos Tsitsipas, Karen Khachanov and Pablo Andujar were also among the round-two winners.

At the Hungarian Open, third seed Richard Gasquet was shocked 6-4 7-6 (7-4) by world number 159 Lorenzo Sonego, while Damir Dzumhur (2) also suffered an early exit in a 6-3 6-1 loss to Marco Cecchinato.

Aljaz Bedene and Jan-Lennard Struff defeated Matteo Berrettini and Alexander Bublik respectively to reach round three.

Mikhail Youzhny moved to within three wins of 500 ATP victories having completed a 6-3 6-3 triumph over Tour debutant Zsombor Piros in a first-round contest held over from Wednesday (AEST).