Blackpool Billinge-born Greenall made his professional debut with
Blackpool on 23 September 1980, at the age of 16 years and 237 days, becoming the club's then-youngest-ever league player (a record broken by
Trevor Sinclair in 1989). Three days later, he appeared in a
League Cup game against
Everton at
Goodison Park. Greenall was one of a host of young players brought to Blackpool by
Alan Ball during his short managerial reign at the club. Unlike most of the others, however, he remained at the club for years and developed into a dependable defender. He eventually took over the central role, combining with captain
Steve Hetzke and
Mike Conroy to form a successful defensive partnership. Greenall won England Youth honours and, at 20, was voted the
Fourth Division's Player of the Year by the
PFA.
Gillingham After 183 league appearances in just over five years, Greenall had a contractual dispute with Blackpool, and in September 1986 he moved to
Third Division Gillingham for £40,000.
Oxford United Greenall joined
Oxford United in February 1988 for £235,000, and the U's soon made him skipper following the departure of
Tommy Caton, as he enjoyed a brief taste of top-flight football before they were relegated at the end of the season.
Bury and Preston North End In July 1990, he moved to
Bury for £100,000 after an initial loan spell at
Gigg Lane, before departing for
Preston North End during
1991–92 – a move in his favour as Preston narrowly beat the drop from
Division Three while Bury were relegated. Preston would follow suit 12 months later, however.
Latter years After a year at
Chester City, where he won promotion and player of the season in
1993–94, and a spell with
Lincoln City, Greenall joined
Wigan Athletic in 1995. At Wigan, he helped guide the team to Third Division success as an ever-present captain in 1997. After coming out of retirement, Greenall made his
Wembley debut in 1999 when he defied his advancing years to help Wigan beat
Millwall 1–0 to win the
Football League Trophy. As of 2021, Greenall summarises for football commentaries on
BBC Radio Lancashire. ==Coaching career==