The club's record attendance was set in August 1997 when 10,603 spectators saw them play Bradford Bulls. On 2 May 1998, having beaten Leigh Centurions, Egremont Rangers, Castleford Tigers and Salford Red Devils, the Eagles faced Wigan Warriors at Wembley Stadium in the final of the Rugby League Challenge Cup. Wigan were overwhelming favourites with a side containing some of the best players of the modern era, including Andy Farrell, Jason Robinson and Henry Paul. Sheffield coach John Kear devised a game plan that was executed perfectly by the team on the day. Star of the show was scrum half Mark Aston, who won the Lance Todd Trophy as man of the match. The Eagles led from start to finish, running out 17–8 winners in one of the biggest upsets in the history of the competition. Just as the club seemed to be on the verge of its greatest period, following the win in the cup final, things began to go wrong. The expected increase in attendances did not happen and the team did not perform well, finishing close to the relegation zone only one year after the Wembley triumph. Finances plummeted and with little outside help it became apparent that the Eagles were not viable in their current state. Just a year after performing the greatest upset in Challenge Cup history, the Eagles announced that they were to fold at the end of the season should no investors come on board to save the club. In late 1999 the Rugby Football League wanted to lower the number of clubs in Super League. One of the measures they put in place was the option for two clubs to merge for the sum of £1,000,000. Fearing this was the only way to keep rugby league alive in Sheffield, the club accepted an offer from the RFL to merge with another struggling team, the Huddersfield Giants, making a new team Huddersfield-Sheffield Giants, who were scheduled to play games in both Sheffield and Huddersfield in Super League V. The Huddersfield-Sheffield side's away strip was in the Sheffield Eagles colours. The merged Huddersfield-Sheffield team did not last the season before reverting to the Huddersfield name. An immediately resurrected Sheffield Eagles would continue in the lower leagues. The merger with Huddersfield was not accepted by Sheffield supporters , and so former player Mark Aston formed a new Eagles phoenix club, earning a place in the Northern Ford Premiership for the 2000 season, taking Bramley's vacated place. From 1999 to the present the Eagles have played in the semi-professional leagues, first the Northern Ford Premiership and then the second division of the LHF Healthplan National League.