Mardy Fish replaced Andy Roddick as the top-ranked American after beating Spain's David Ferrer 7-5, 6-2 on Wednesday to move into the semi-finals of the Sony Ericsson Open.
Defending champion Andy Roddick made a shock early exit from the Sony Ericsson Open on Saturday, suffering a second round loss to Uruguayan Pablo Cuevas 6-4, 7-6.
15-year-old American Ryan Harrison beat Uruguayan Pablo Cuevas 6-4, 6-3 at the US Men's Clay Court Championship.
Former French Open finalist Guillermo Coria lost in the first round of the Vina del Mar International.
Rafael Nadal and Novak Djokovic won their matches for their respective countries on Day 4 of the ATP Cup on Monday.
Rafa Nadal's below-par season has continued with the former world number one dumped from the Rio Open semi-finals with a 6-7(6) 7-6(3) 6-4 defeat by unseeded Uruguayan Pablo Cuevas on Saturday. The top seed pipped Cuevas in a first set tie-break and denied his opponent two set points in the second but succumbed to his first defeat against the world number 45. "I lost an opportunity, that's it," Spaniard Nadal said after being denied his 100th ATP final by claycourt specialist Cuevas who fired 48 winners to clinch the contest. "I fought until the end. I have to accept it and keep working to try to change the dynamic. That's what's happening today and I have to work hard to change it," added the 14-times grand slam champion. "I didn't win a title, so it wasn't a positive two tournaments. I had my chances in both. I lost in the semi-finals of both tournaments and just have to look forward to Indian Wells."
Fabio Fognini pulled off a huge upset, stunning top seed and holder Rafael Nadal 1-6, 6-2, 7-5 in the Rio Open semi-final on Saturday.
The positive cases were recorded after the charter flight from Los Angeles landed in Melbourne for the tennis Grand Slam, according to online posts from players.
World number one Novak Djokovic survived a second set fightback from Slovak Martin Klizan before winning his opening match at the Miami Open 6-0, 5-7, 6-1.
A red hot Rafael Nadal ended a seven-match losing streak against Novak Djokovic in emphatic fashion by thrashing the world number two 6-2, 6-4 on Saturday to reach the final of the Madrid Open and move within a step of a third consecutive clay-court title.
World number one Rafael Nadal set a new record of winning 50 consecutive sets on a single surface by beating Argentine Diego Schwartzman 6-3, 6-4 on Thursday to reach the Madrid Open quarter-finals.
Images from Day 5 of the French Open, at Roland Garros, in Paris.
Garbine Muguruza's preparations for next week's Australian Open were thrown into disarray when the world number three pulled out of the Sydney International with a thigh injury on Wednesday.