Juninho gave Middlesbrough a well-deserved lead to take to their Carling Cup semi-final second leg against Arsenal at the Riverside next Wednesday.
The Brazilian scored the only goal after 52 minutes, beating keeper Graham Stack with a right-foot cross-shot from Gaizka Mendieta's pass, after Martin Keown misplaced a clearance under pressure.
Juninho had fired a first-half effort against an upright with Stack beaten and two minutes before the goal, his curling shot forced a flying save from the Arsenal keeper.
Boro could have stretched their lead further. Stack saved at full length from Massimo Maccarone after 62 minutes and Joseph-Desire Job missed two late chances. He was robbed by Gael Clichy when Boro broke two-on-one, then blazed wide from Stuart Parnaby's cross.
Juninho said: "I felt a bit unlucky with the first shot, but I made up for it later. We could have taken a bigger lead. Arsenal rested a lot of players but they're still a strong team." Ugo Ehiogu, who marshalled the Boro defence superbly, said: "I was disappointed that we didn't score a second, but we've given ourselves a decent chance of reaching the final." It was only Boro's second win at Highbury in 65 years and manager Steve McClaren's first against Arsenal after seven successive defeats.
He said: "I'm very satisfied. We defended very well. We grew in belief as the game went on and passed the ball well. Now we have to be ready and perform again in the second leg." The Gunners were a pale shadow of the side that crushed Boro 4-1 in the Premiership ten days ago. Boss Arsene Wenger rested Thierry Henry, Robert Pires, Freddie Ljungberg, Patrick Vieira and Sol Campbell. Dennis Bergkamp, Sylvain Wiltord and Jeremie Aliadiere were out injured.
The tireless Edu was Arsenal's star, but toiled with scant support. The Gunners lacked cohesion and penetration.
Boro keeper Mark Schwarzer had only one direct shot save to save, a 72nd-minute strike by David Bentley. Kolo Toure, Edu and Kanu were all off target when well placed.
Boro's win presents Wenger with selection questions for the second leg and the FA Cup tie at home to Boro on Saturday.
But he insisted that he would stick with his youngsters for the return at the Riverside. He added: "We could have got something out of tonight's match. The tie is not over yet." The winners meet Bolton or Aston Villa in the final.