"The time is right for Juninho to return to the club for a third time. We are progressing from last season and I believe Juninho is the final piece of the jigsaw."
Chief executive Keith Lamb revealed that Boro had snapped up Juninho for a bargain £3.8m. It was widely reported that Boro had agreed a £6m fee with Athletico Madrid, but it turns out that this was in fact 6m Euros.
Juninho's signing follows those of Franck Queudrue (£2.5m), Massimo Maccarone (£8.15m), George Boateng (£5m) and Geremi (loan) and brings Boro outgoings close to £20m.
Juninho said "I am very happy to be back at Middlesbrough. I feel at home. Whenever I have thought of England I have thought of Middlesbrough."
"The manager was used to winning things at Manchester United and I hope to win something at Middlesbrough. I think the club is capable of doing better than ever before. There are some very good players here and I believe we will do well."
Boro fans will get the chance to welcome him back on Wednesday when he takes part in the friendly against Alaves at the Riverside. Although his international clearance papers have not yet come through Boro have received special permission for him to play. So get yourself there early, there could be a decent crowd, kick-off is 7.45pm.