Novak Djokovic and Rafael Nadal progress at Indian Wells

Djokovic is pursuing a fifth title at Indian Wells, and a third straight success in the California desert.

He meets Spain's Lopez in the last 16, the only man to beat him this year after a completing a surprise win in last month's Dubai quater-final.

"I allowed myself twice to lose serve when I was a break up in both sets," said Djokovic of his win over Kohlschreiber.

"Those things cannot happen. I cannot allow myself any more to react that way in those particular circumstances.

"I was fortunate today to manage to win in straight sets. But Kohlschreiber is an experienced player. He has played so many times on the big occasions, so he knows how to capitalize on the opportunities and come back into the match.

"I just put myself in a very difficult position after that. But there are more positive things I can take out of this match today comparing it with the first one."

Rafael Nadal defeated Spanish compatriot Fernando Verdasco 6-0 7-6(9), serving up a bit of payback for the loss to him in the opening round of the Australian Open in January.

Nadal dominated early before digging in late in the second set to put the match away, saving five set points in the tie-break to triumph after falling 6-3 behind.

"I lost matches similar to this one in Australia, in Buenos Aires, in Rio de Janeiro, so it's important winning matches like this for me," said Nadal. "Like the other day in the third (against Gilles Muller), today in the second.

"I knew arriving to a tie-break against a player like Verdasco, normally he serves better than me. Normally in these kind of matches I have more to lose than him, so he's able to play very aggressive. He has amazing shots. He gets in a tie-break and you know you're in trouble.

"I feel lucky to win the tie-break, and at the same time I think at the end of the tie-break I played well with not many mistakes and going for the points. It is an important victory for me. Two tough wins here. That's something that stays in my mind and helps."

Japan’s fifth seed Kei Nishikori prevailed from two tight tie-breaks to reach the fourth round with victory over Steve Johnson.

It may have been an entirely different outcome, had American Johnson converted his 6-2 lead in the opening breaker into a one-set advantage, but Nishikori eventually came through 7-6(6) 7-6(5) in one hour and 56 minutes.

The 26-year-old will face John Isner, a 6-4 7-6(4) winner against Adrian Mannarino, in the next round.

"It's not easy with these windy conditions and the ball and altitude, everything," said Nishikori. "It's tough to expect great tennis here, but I thought I was patient today and had a good first match.

"Obviously, it's not easy, but I have been playing good tennis these two matches and having confidence winning today, too. So I'm looking forward to playing my next match."

There was a mini shock in another early clash on Tuesday as 16th seed Gilles Simon slumped to a 6-2 6-2 defeat to Germany’s 18-year-old Alexander Zverev.

"I thought I played really well today," said Zverev. "I think I was really aggressive. Hit a lot of winners. Beating someone like Gilles 6-2, 6-2 is something that gives me a lot of confidence for myself. He's such a great player and such a tough competitor, as well.

"I was really ready for a long, long fight and a long three-set match and that was that quick. I'm really happy that I got through so quickly."

France's Jo-Wilfried Tsonga also defeated American Sam Querrey 6-3 6-4 in other results.

9-John Isner (US) beat Adrian Mannarino (France) 6-4 7-6(4)

6-Kei Nishikori (Japan) beat 30-Steve Johnson (US) 7-6(6) 7-6(5)

Alexander Zverev (Germany) beat 16-Gilles Simon (France) 6-2 6-2

5-Rafael Nadal (Spain) beat Fernando Verdasco (Spain) 6-0 7-6

7-Jo-Wilfried Tsonga (France) beat Sam Querrey (US) 6-3 6-4

1-Novak Djokovic (Serbia) beat Philipp Kohlschreiber (Germany) 7-5 7-5