World number one Novak Djokovic secured his place in the last 16 at the Madrid Open with a straight-sets win over training partner Borna Coric.
The Serbian top seed, who had a bye through from round one, came through 6-2 6-4 against the 19-year-old Croat, and will next face Roberto Bautista Agut of Spain.
Djokovic has spent time working with Coric and believes the 6ft 1ins teenager, ranked 40 in the world, has a bright future.
"We know each other well. We have practice many times. I do see myself in him a little bit. We play a similar style. He's a great fighter," Djokovic said to www.atpworldtour.com.
"For his age, he is quite mature and mentally tough. We have a very nice relationship.
"Today was the first official match we have played against each other, so I was happy with my performance. It was a fun match to be part of."
Bautista Agut, seeded 15, progressed following a testing match against compatriot Feliciano Lopez, taking almost three hours to complete a 6-3 5-7 7-5 victory.
Another Spaniard into round three is David Ferrer, who beat American qualifier Denis Kudla 6-4 4-6 6-4. The ninth seed will next face T omas Berdych after the Czech world number eight saw off Uzbekistan qualifier Denis Istomin 6-3 6-3.
Australian Nick Kyrgios put out Stan Wawrinka, the world number four, after coming through a tie-break in each set to win 7-6 (9/7) 7-6 (7/2).
Next up for Kyrgios will be Uruguan Pablo Cuevas, who produced a surprise win in three sets to knock out number 13 seed Gael Monfils 6-7 (5/7) 6-3 7-6 (7/4).
Gilles Simon, the 16th seed, is also through having come from behind to beat Pablo Carreno-Busta 2-6 6-3 6-4, and will take on Great Britain's Andy Murray in the third round, while Japan's six seed Kei Nishikori saw off Italian Fabio Fognini, again in three sets 6-2 3-6 7-5.
Sam Querrey set up a clash with Rafael Nadal after battling to a 6-7 (5-7) 6-3 6-4 victory over Lucas Pouille of France, while another American, Jack Sock, defeated Juan Martin del Potro 6-4 7-6 (7/2).
Seventh seed Jo-Wilfried Tsonga progressed in the day's last match to finish, seeing off home hope Albert Ramos-Vinolas 7-6 (8/6) 5-7 6-4.
World number five Victoria Azarenka was forced to withdraw from the women's tournament due to a lower back injury.
The two-time Australian Open champion, seeded fourth, was set to meet Louisa Chirico in the third round, so the American was given a walkover.
Petra Kvitova, the fifth seed, was another of the leading names to exit on Wednesday, losing 6-3 6-4 to Australia's Daria Gavrilova.
Elsewhere, Australian Samantha Stosur came from behind to put out eight seeded Spaniard Carla Suarez Navarro 4-6 6-2 6-3.
Romania's Simona Halep is the highest seed left in the tournament at number six, after she defeated Timea Bacsinszky of Switzerland 6-2 6-3.