Boro were knocked out of the EFL Cup on Wednesday after they were beaten in extra time by Fulham at Craven Cottage.
Even so, Karanka believes his side can respond to the disappointment when they switch their attentions back to the Premier League tomorrow afternoon.
Disappointment in the cup
“After the game on Wednesday, the team knows we need to win again,” Karanka said in his pre-match press conference.
He added that, "we have to move on" because the cup was "disappointing for everyone."
Boro have made a good start to the new campaign following their promotion from the Championship in May.
After a 1-1 draw with Stoke on the opening weekend, Boro recorded their first victory season away at Sunderland last weekend and Karanka is hopeful of building some momentum.
Sunderland victory provides momentum
“Mistakes in the Premier League cost three points. The players know how important it is to add points, especially at the beginning of the season," said the Boro boss
We are looking forward to the game (against West Brom) because in the league we are in a good position and we have to keep this momentum going.”
Karanka added that “You can always believe" although it is "easier when you have three points on the table."
For this reason, Karanka feels that "the win [against Sunderland] was really important, especially as a derby."
Boro’s trip to The Hawthorns will see Karanka come up against West Brom manager Tony Pulis for the first time in their respective managerial careers.
The Baggies were also eliminated from the cup in extra time on Tuesday night after they were beaten by Northampton.
Nevertheless, Karanka was still full of praise for his opposite number ahead of tomorrow’s meeting.
Respect for Pulis
"I have a lot of respect for Tony [Pulis]. Since the first day I met him he showed me he is a gentleman,” expressed Karanka.
The Spaniard feels this way about his counterpart because “he is experienced, and has never been relegated from the Premier League."
He added that, "he is an amazing manager and I have learned a lot from him."
“West Brom is a team that plays with a plan. They are a strong team and are strong from set pieces. But we have to think about ourselves.”