Champion Serena Williams swatted aside the limp challenge of Elina Svitolina 6-1 6-1 on Wednesday, to reach the quarter-finals of the French Open.

The world number one rarely sparkled on a damp, dank centre court at Roland Garros, but always wielded enough firepower to see off the Ukrainian 18th seed in a match that was delayed by two days due to the fickle Parisian weather.

Although spluttering from time to time -- Williams fired the odd serve alarmingly long; netted the occasional simple groundstroke -- the top seed always did enough to neuter her scurrying opponent.

The American will play Carla Suarez Navarro or Yulia Putintzeva for a spot in the semis.