Wallace trailed Joe Perry 0–2 but recovered to win convincingly, 10–4, and thus reached the final stages at the Crucible Theatre for the first time. At the Crucible, he was drawn against Alan McManus and, against expectations, Wallace prevailed 10–2; he then won his next match 13–5 against Mark King to reach the quarter-finals. Drawn to play his friend and fellow countryman Joe Swail, this match proved a tighter affair; Wallace led 6–2 and 7–4 but could not prevent an 11–13 loss. Assured of £36,500 in prize money, he went into the 2001/2002 season ranked 34th, his highest-ever position. The season did not reflect his impressive result at the World Championship, as he could not progress beyond the last 48 in any of the eleven tournaments he entered, and 2002–03 was no better; although he again came within one win of reaching the Crucible, Ali Carter beat him 10–8, and his ranking for the 2003/2004 season dropped to 50th. In the years that followed, Wallace struggled for results, his ranking eventually falling to 74th in the 2005/2006 season, and accordingly he was relegated from the tour again in 2006. He won the Northern Ireland Amateur Championship for the third time in 2007, defeating Joe Meara 10–5 in the final, and received a wildcard to compete again on the main tour as the Northern Ireland nomination; however, he could not recapture the stellar form he showed in 2001, and from this point until his latest relegation from the tour in 2011, he never broke back into the top 64. He remains the only player ever to have reached the quarter-finals of the World Championship in their only appearance at the televised stages. After retiring in 2011, Wallace participated in the qualifying rounds for the 2012 World Snooker Championship. He defeated John Parrott 5–0 in the first preliminary qualifying round before beating Joe Delaney 5–2 in the second preliminary round; however, he was defeated in the second qualifying round 10–9 by Yu Delu. Amateur Since retiring as a professional Wallace has continued as an amateur, and has won the Northern Ireland Championship a record eight times; he had been holding the title between 2012 and 2016. In 2016 Wallace received an invitation as a wildcard to the 2016 Northern Ireland Open, where he lost in the first round 2–4 to Michael Georgiou. Having qualified for the 2018 World Seniors Championship, he came