Boro began their UEFA Cup campaign in the qualifying round in September. They beat Greek side Xanthi 2-0 at the Riverside Stadium and drew 0-0 in the second leg in Greece, which earned them a place in the group stage.
Middlesbrough met Grasshoppers Zurich in their first group game. Jimmy Floyd Hasselbaink scored the only goal in the 10th minute to secure the three points. Boro then beat Dnipro 3-0 at home and all but secured their place in the knockout rounds.
After a 0-0 draw with Dutch side AZ Alkmaar, Boro faced Bulgarian club Litex Lovech. Massimo Maccarone produced his first really good performance of the competition, scoring twice in the last ten minutes to secure first place in the group.
The long cup run continued with two very difficult matches against Stuttgart. McClaren's players won 2-1 in Germany and, despite losing 1-0 at home, went through to the next round.
Roma awaited in the last 16. Yakubu scored a penalty in the 12th minute of the first leg at the Riverside. Boro then lost 2-1 in Italy, but Hasselbaink's away goal took them into the quarter-finals.
What made the run so special came next. In the quarter-finals Middlesbrough lost the first leg 2-0 in Basel, then conceded an early goal in the return. McClaren's side suddenly needed four goals to go through, a task that looked almost impossible, and they got them, with Maccarone scoring in the very last minute to send Boro into the semi-finals.
In the semi-finals Middlesbrough lost the first leg 1-0 to Steaua and then conceded two early goals at the Riverside. Once again they needed four goals, once again the crowd at the Riverside refused to give up, and once again Maccarone scored the fourth in the final minute, this time with a superb header.
In the final Boro were unlucky and lost 4-0 to Sevilla. Even so, the cup run was an incredible achievement for Middlesbrough. The club are now in the Championship but very close to a return to the Premier League, and their supporters will hope for something like that European adventure again.
The final in Eindhoven
The final was played at the Philips Stadion in Eindhoven on 10 May 2006 and was the first European final for both clubs. Sevilla took the lead through Luís Fabiano in the 27th minute, and the game slipped away from Middlesbrough late on: Enzo Maresca scored in the 78th and 84th minutes, and Frédéric Kanouté added a fourth in the 89th. The German referee Herbert Fandel took charge of the match.
What came next for McClaren and Boro
The final was Steve McClaren's last big occasion with the club. Days before it, the Football Association had named him as Sven-Göran Eriksson's successor as England manager, with the job starting on 1 August 2006, and he described the UEFA Cup final as his immediate priority. His time in charge of England ended in November 2007, when he was sacked after the team failed to qualify for Euro 2008.
The return to the top flight that Boro supporters hoped for came at the end of the 2015/16 Championship season. On the final day Middlesbrough drew 1-1 with Brighton & Hove Albion in a direct promotion decider, Cristhian Stuani scoring for Boro. Both clubs finished on 89 points, and Aitor Karanka's side went up as runners-up on goal difference, having conceded only 31 league goals all season.
Questions people ask
Who did Middlesbrough play in the 2006 UEFA Cup final?
Middlesbrough played Sevilla at the Philips Stadion in Eindhoven on 10 May 2006 and lost 4-0. It was the first European final for both clubs.
Who scored the goals in the 2006 UEFA Cup final?
Luís Fabiano gave Sevilla the lead in the 27th minute, Enzo Maresca scored twice in the 78th and 84th minutes, and Frédéric Kanouté added the fourth in the 89th.
Who managed Middlesbrough during the 2005/06 UEFA Cup run?
Steve McClaren managed Middlesbrough. Shortly before the final the Football Association named him as the next England manager, a job he started on 1 August 2006.
When were Middlesbrough promoted back to the Premier League?
Middlesbrough won promotion at the end of the 2015/16 Championship season under Aitor Karanka. A 1-1 draw with Brighton on the final day left both clubs on 89 points, and Boro went up as runners-up on goal difference.