The team finishing fourth in League One has won promotion via the play-offs in each of the last three seasons.
Despite that, since the current format was introduced in 1988/89, the team finishing third has won the play-offs more often than any other position in the third tier (eight, fourth has won six).
Rotherham have never won promotion via the play-offs in three previous attempts; they have reached the final once before, losing to Dagenham and Redbridge (3-2) in 2010.
The Millers and the O’s met in the semi-finals of the fourth tier play-offs in 1998/99. After two 0-0 draws, Orient won 4-2 on penalties to progress.
The East Londoners won the fourth tier play-offs in 1988/89 but have lost their two campaigns in them since that victory, most recently in 2000/01.
Leyton Orient have only won two of their last 19 meetings with Rotherham in all competitions (D9 L8).
Rotherham have not played in the Championship since 2004/05, when they won just five games all season and finished bottom.
The O’s have not played in the second tier, meanwhile, since 1981/82; their last 32 campaigns have all been in either the third or fourth tiers.
Russell Slade’s side scored in 42 of their 46 regular league games this season, the most in League One, and also netted in both play-off semi-finals.
Kieran Agard has scored five goals in his last five appearances for the Millers.
Rotherham and Leyton Orient have both won six games from losing positions in League One (including play-offs) this season; a joint-league-high.
Steve Evans’ side have scored 17 goals in the opening 15 minutes of league games this season (including play-offs), while the O’s have managed just six.
Orient have conceded a league-high 30% of their goals to headers this season (including play-offs).