World number 14 Goffin missed Wimbledon after suffering the injury in his French Open third-round match with Horacio Zeballos.

Goffin received a wildcard for the clay-court event in Umag but the top seed did not have it all his own way in the second-round clash.

After breaking Balazs's serve twice en route to the first set, Goffin squandered two match points in the second-set tie-break as the Hungarian forced a decider. However, the Belgian recovered an easily took the third to win 6-4 6-7 (7-9) 6-2.

Fourth seed Paolo Lorenzi and eighth seed Jiri Vesely were also victorious - beating Aljaz Bedene and Radu Albot respectively - while Ivan Dodig overcame Marco Cecchinato.

The top seed at the Swedish Open did not enjoy the same fortune, as Pablo Carreno Busta retired in the third set against Andrey Kuznetsov having failed to serve out the match in the second.

Carreno Busta, ranked 16th in the world, had not played since his quarter-final loss to Rafael Nadal at the French Open because of an abdominal injury, and the same issue flared up again in Bastad.

He broke for a 5-3 lead in a second set in which both players' serve came under consistent pressure, only to allow the Russian to immediately hit back and go on to win the tie-break to force a third.

Kuznetsov then rattled off the first three games of the third before Carreno Busta decided he could not continue.

Third seed Pablo Cuevas was also knocked out in the second round - losing 6-4 6-3 to Henri Laaksonen - but seventh seed Diego Schwartzman beat Argentine compatriot Renzo Olivo in straight sets and David Ferrer needed only 55 minutes to defeat Dustin Brown.

On the grass in Newport, John Isner made short work of qualifier Sam Groth at the Hall of Fame Open in a 6-2 6-4 success, and defending champion Ivo Karlovic sent down 16 aces to beat Denis Kudla 6-4 6-4.

Fourth seed Pierre-Hugues Herbert needed three sets to see off Adrian Menendez-Maceiras, but third seed Adrian Mannarino lost to Tobias Kamke and sixth seed Lukas Lacko was stunned by qualifier Matthew Ebden.

Dennis Novikov and Bjorn Fratangelo also reached the quarter-finals in Rhode Island.