Both men were faultless on their own serve in the first set, with the only break point going Raonic's way in the final game. He could not take advantage of that, however, and the set went to a tie-break that saw Lopez win 7-4.
After such a strong display of serving in the first set, it was a surprise when Raonic broke Lopez in the very first game of the second, and the Canadian held on to his serve for the remainder of the set to take it 6-4.
It was more of the same in the third set, with Raonic breaking in the first game before holding on to his serve and eventually breaking again in the final game of the set to take it 6-3.
The fourth set went with serve until what turned out to be the final game as Raonic took the second of two match points to book his place in the next round, where he will face either Richard Gasquet or Dmitry Tursunov.