Coventry were struggling back in November and the choice to fire popular manager Mark Robins was a controversial one despite the club sitting 17th in the Championship standings.
However, an impressive turnaround under new boss Frank Lampard silenced the critics with the Sky Blues now just a possible 270 minutes away from returning to the English top flight.
Cov have secured victory in 16 of their 29 league matches under the former Chelsea and Everton coach and they have perfectly timed their play-off run, winning seven of their last eight matches at home.
They seemed to be losing momentum last month with losses to Luton and Plymouth jeopardizing their chances of making the top six, but last Saturday's 2-0 victory over Middlesbrough secured a fifth-place finish and an opportunity to strive for promotion to the Premier League.
On the other hand, Sunderland appear to be struggling at a critical moment, entering the play-offs after a run of six matches without a win.
The Black Cats delivered their best performances earlier in the season and spent a significant portion of the campaign in the play-off positions.
Team news
First-choice goalkeeper Oliver Dovin (knee) is expected to be absent once again for Coventry, leading to Ben Wilson taking his place in goal for Friday's first leg.
Injured duo Ephron Mason-Clark (foot) and Norman Bassette (hip) will also be sidelined for the Sky Blues following a busy recent schedule.
Victor Torp is also unavailable, so Matt Grimes could partner Ben Sheaf once more in central midfield.
Sunderland are facing the absence of several key players, with Romaine Mundle (hamstring) and Ian Poveda (leg) likely to return to action in about a week.
The stats
Sunderland have been defeated in their last five matches.
Coventry have won 16 of 29 league matches under Lampard's management.
Cov have won seven of their last eight matches at home.
The Sky Blues defeated Sunderland 3-0 in March.
Sunderland have not managed to beat Coventry in 10 encounters, a streak dating back to 2007.
The Black Cats have scored only one goal in their last five matches.
Prediction
Coventry convincingly outperformed Sunderland as recently as March, and the in-form Sky Blues are predicted to achieve a similar result to their 3-0 victory two months ago.
The Black Cats have been underwhelming in recent weeks and their play-off qualification was largely secured through their strong performances earlier in the season.
They have a poor recent record against Coventry, and their 10-match winless streak against the Sky Blues appears likely to continue.
Cov are formidable at home and are expected to secure a win ahead of their play-off semi-final second leg at the Stadium of Light next Tuesday.