Serena Williams, a 23-time Grand Slam singles champion, and second-ranked Spaniard Carlos Alcaraz, a seven-time Slam singles winner, will compete together in US Open mixed doubles, organizers announced Saturday. The 23-time Grand Slam champion will not be playing singles, but could team up with her older sister Venus for doubles. Key points and original sources are listed below.

• Serena Williams, a 23-time Grand Slam singles champion, and second-ranked Spaniard Carlos Alcaraz, a seven-time Slam singles winner, will compete together in US Open mixed doubles, organizers announced Saturday. The US Tennis Association announced mixed double...S1

• The 23-time Grand Slam champion will not be playing singles, but could team up with her older sister Venus for doubles.S2