McClaren: Juninho saved Marinelli
Marinelli was loaned out last season after slipping out of McClaren's plans, but no permanent move has arrived.
However, rather than allowing the discontent to grow, it appear that Juninho has helped the player come to terms with the need to earn a place, and allowed the Argentine to battle his way back to contention.
"He [Marinelli] lost his place, got frustrated with himself and others and wasn't mature enough to handle it," explained McClaren.
"Carlos had opportunities to go , but decided to stay and fight for his place.
"He's worked so hard in pre-season he's forced his way into the reckoning.
"His attitude is great now, and it's all because of Juninho.
"Juninho took Carlos under his wing at the end of the season and he's spoken to him at length.
"He is a big influence here and it has a huge effect.
"Juninho has done this on his own initiative, we didn't ask him to do it, but it's producing results."
Meanwhile, Middlesbrough have been linked with a move for Spanish superstar Gaizka Mendieta.
The former Valencia man established himself as one of the premier footballers in the world whilst in Spain, but a blockbuster move to Lazio brought the player back down to earth with a bump.
After failing to have any impact on the Italian game, Mendieta was loaned back to Spain and Barcelona, but again did not produce the goods, and is looking to recapture his past form.