World number two Roger Federer is on course for an 8th Basel Open title after he came from a set down to beat French Opponent Adrian Mannarino in three sets during their quarterfinal clash.
The top seed saw off Mannarino 4-6 6-1 6-3 to book his place in the last four where he will meet David Goffin of Belgium on Saturday. Goffin defeated American Jack Sock 7-6 (8-6) 6-3 to reach the semis.
In the other semifinal, world number four Marin Cilic will take on Juan Martin del Potro of Argentina.
Croatian star Cilic beat 100th-ranked Hungarian Marton Fucsovics 7-6(3) 5-7 7-6(4) in just over three hours to secure a last four place while Juan Martin del Potro got the better of Roberto Bautista 6-2 2-6 6-4 to stay in contention for the last two ATP World Tour Finals spots in London.