2018 Davis Cup
The 2018 Davis Cup was the 107th edition of the Davis Cup, a tournament between national teams in men's tennis. It was sponsored by BNP Paribas. In 2018, new rules were introduced for the Group I and II zonal events, with ties now being played as best-of-three sets over the course of two days.
Croatia won their second Davis Cup on indoor clay in the final match held at 25 November with a 3–1 win over France.
World Group play-offs
Date: 14–16 September 2018The eight losing teams in the World Group first round ties and eight winners of the Zonal Group I final round ties will compete in the World Group play-offs for seeded spots in the 2019 Qualifying Round. Seedings are based on Davis Cup rankings as of 9 April 2018.
Seeded teams
| Home team | Score | Visiting team | Location | Venue | Door | Surface |
| ' | 4–0 | San Juan | Estadio Aldo Cantoni | Indoor | Clay | |
| ' | 3–1 | Glasgow | Commonwealth Arena | Indoor | Hard | |
| ' | 3–1 | Graz | Messe Congress Graz | Outdoor | Clay | |
| 2–3 | ' | Biel/Bienne | Swiss Tennis Arena | Indoor | Hard | |
| ' | 4–0 | Kraljevo | Kraljevo Sports Hall | Indoor | Clay | |
| ' | 3–1 | Toronto | Coca-Cola Coliseum | Indoor | Hard | |
| 2–3 | ' | Budapest | Kopaszi Dam | Outdoor | Clay | |
| ' | 4–0 | Osaka | Utsubo Tennis Center | Outdoor | Hard |
Americas Zone
Group III
Date: 28 May–2 JuneLocation: Costa Rica Country Club, Escazú, Costa Rica
Format: Round-robin basis. The winner of Pool A will play-off against the runner-up of Pool B and the winner of Pool B will play-off against the runner-up of Pool A to determine which two nations will advance to Americas Zone Group II in 2019.
;Participating teams
;Pool A
;Pool B'
- '
Play-offs
' and ' promoted to Group II in 2019.Asia/Oceania Zone
Group III
Date: 2–7 AprilLocation: Mỹ Đình Sports Complex, Hanoi, Vietnam
Format: Round-robin basis. One pool of 4 teams and one pool of 5 teams. The winner of Pool A will play-off against the runner-up of Pool B and the winner of Pool B will play-off against the runner-up of Pool A to determine which two nations will be promoted to Asia/Oceania Zone Group II in 2019.
;Participating teams
;Pool A''
;Pool B
- '
Play-offs
' and ' promoted to Group II in 2019.' and ' relegated to Group IV in 2019.Group IV
Date: 29 January–3 FebruaryLocation: Sultan Qaboos Sports Complex, Muscat, Oman
Format: Round-robin basis. Two pools of six teams. The winner of Pool A will play-off against the runner-up in Pool B and the winner of Pool B will play-off against the runner-up in Pool A to determine which two nations will be promoted to Asia/Oceania Zone Group III in 2019.
;Participating teams
;Pool A'
;Pool B
- '
Play-offs
' and ' were promoted to Group III in 2019.Europe/Africa Zone
Group III Europe
Date: 3–7 AprilLocation 1: Tennis Club Lokomotiv, Plovdiv, Bulgaria
Location 2: Ulcinj Bellevue, Ulcinj, Montenegro
Format: Round-robin basis. Two pools of four teams at each venue. The winners of each pool play-off against each other to determine which nation will be promoted to Europe/Africa Zone Group II in 2019. Two promoted - one from each venue.
;Participating teams
;Pool A (Plovdiv)
;Pool B (Plovdiv)'
;Pool A (Ulcinj)
- '
*
Play-offs
' and ' were promoted to Group II in 2019.Group III Africa
Date: 18–23 JuneLocation: Nairobi Club Ground, Nairobi, Kenya
Format: Round-robin basis. One pool of four teams and one pool of five teams. The winners of each pool play-off against each other to determine which two nations are promoted to Europe/Africa Zone Group II in 2019.
;Participating teams
;Pool A
;Pool B'
- '