|Born||17 March 1961|
|Height||1.90 m (6 ft 3 in)|
|Highest ranking||No. 94 (3 Oct 1988)|
|Grand Slam Singles results|
|French Open||2R (1985)|
|US Open||1R (1985)|
|Highest ranking||No. 184 (2 Jan 1984)|
|Grand Slam Doubles results|
|French Open||2R (1982)|
|Grand Slam Mixed Doubles results|
|French Open||QF (1986)|
Viver was the world number one ranked junior player in 1979, the year that he won the Orange Bowl (18s & Under). He also reached his only semi-final on the Grand Prix tennis circuit in 1979, at Bogota.
In the 1982 French Open, Viver and partner Luca Bottazzi had a win over fifth seeds Anders Järryd and Hans Simonsson, but lost in the second round. Three years later he won his only Grand Slam singles match, over world number 42 John Fitzgerald. He was a mixed doubles quarter-finalist in the 1986 French Open, with Mariana Perez-Roldan.
He appeared in 18 Davis Cup ties for Ecuador during his career, from 1978 to 1990. In the mid-1980s he was part of the team which competed in the World Group and faced players like Jimmy Arias, Boris Becker and Miloslav Mečíř. Viver finished with a 15/13 overall record, winning 14 of his 25 singles rubbers.
|1.||1988||Neu-Ulm, West Germany||Clay||Stefan Eriksson||7–5, 6–2|
|2.||1991||Pembroke Pines, United States||Clay||Jimmy Brown||6–3, 1–6, 7–6|
|3.||1991||São Paulo, Brazil||Clay||Gabriel Markus||7–6, 3–6, 6–3|
|1.||1982||Brussels, Belgium||Clay||Alberto Tous|| David Graham
|3–6, 6–3, 7–5|
|2.||1983||Brescia, Italy||Iván Camus|| Dacio Campos
|6–2, 5–7, 6–4|
|3.||1988||Nyon, Switzerland||Clay||Hugo Nunez|| Jan Apell
|2–6, 6–4, 6–1|