Rafael Nadal swept past Kevin Anderson in straight sets on Thursday to maintain his unbeaten start to the clay-court season and move into the quarter-finals of the Barcelona Open.

Playing on the court that was officially named in his honour this week, Nadal swiftly seized control of a contest delayed by morning rain and never looked likely to be denied his 50th career win at the ATP 500 event.

The Spaniard, who is seeking a 10th title in Barcelona having achieved the same feat in Monte Carlo last week, ultimately triumphed 6-3 6-4 and will now face Hyeon Chung or Alexander Zverev in the last eight.

Anderson came into the match as a huge underdog and his hopes of pulling off a shock were soon dented as he slumped 3-0 down.

Although Nadal was guilty of more errors than he would have liked, the third seed nevertheless remained firmly in control and wrapped up the opening set with an eye-catching forehand winner.

The start of set two brought a notable lift in quality, Anderson digging deep and producing his best tennis of the match to save four break points in an enthralling first game.

However, Nadal's superior movement and shot-making ability was rewarded as he broke at the next time of asking.

Anderson battled on gamely thereafter, his powerful serve predictably earning a number of free points, but the South African was unable to make any impression on the Nadal serve as the former world number one maintained his 100 per cent record in meetings between the two.