Seems like everyone's going on a six-game streak these days: Fabiano Caruana (who made it to seven games), Alexander Grischuk, Anish Giri, Vladimir Kramnik and Magnus Carlsen, to name a few super-GMs to have accomplished the feat since last year's Sinquefield Cup. Hikaru Nakamura added his name to their ranks with a victory over Veselin Topalov in the Gibraltar Masters Open, thereby maintaining a half point lead over David Howell (who ground out a win in a very long game against the world's youngest-ever ex-2700, Wei Yi) and Yu Yangyi (who beat Renier Vazquez Igarza).
Nakamura will have the black pieces against Howell in round 7, while Yu will have the first move against his countrywoman Hou Yifan, who is among the 5-pointers. Both games ought to be extremely interesting. Other prominent pairings are Wagner-Bachmann and Adhiban-Naroditsky. (These are the remaining players with five points.)
Other U.S. notables: Aleks Lenderman drew with the 2551-rated Grigory Oparin, and as a reward he'll have Black against Topalov. (Both have 4.5.) Irina Krush and John Watson both won their games to get to 4/6, but rusty James Tarjan lost and remains at 3. Krush and Watson will face strong GMs next round (David Anton Guijarro and Gawain Jones, respectively).
Top games can be replayed here or here (the latter links lets you access the games with computer analysis and the video commentary too).