The Basque club, coached by the eccentric Marcelo Bielsa, are aiming for a meeting on May 9 against Atletico Madrid or Valencia, who start the other semi-final at the Calderon on Thursday.
Goikoetxea was part of the Athletic side knocked out of the old UEFA Cup by Sporting 27 years ago, the only previous meeting between the sides.
"It will be tough but I'm optimistic because I think Athletic are a better team, and for this reason I'm convinced they will play the final," the former Spain international told Marca.
"This team has the chance to make history. They already have a Copa del Rey final (against Barcelona next month) and we'll see what happens in the Europa League."
Athletic have never won a European trophy but have thrilled neutral fans with a 5-3 aggregate victory over Manchester United and a 6-4 roller-coaster win over Schalke 04 in the quarter-finals.
The club, who only field Basque-born players, have been praised for their dynamic, attack-minded approach, particularly on the road where they scored three times at Old Trafford and four in Gelsenkirchen. They start their semi in Lisbon.
"Athletic have a clearly defined style and they never go out to defend," Goikoetxea added. "They are very quick, and are very strong down the flanks.
"Their best games have been against the big clubs, especially against Manchester United, and for that reason they have won European-wide recognition."
Sporting have been revitalised under new coach Ricardo Sa Pinto and claimed the scalp of big-spending Manchester City in the round of 16.
"We did not concede any goals against Manchester City and then scored away and that is fundamental in the knockout stage," Sporting's Brazilian midfielder Elias told the club website.
"We must defend well at home, look to score and then, with the quality we have, I am sure we will get away goals."
The other semi-final pitches 2010 Europa League winners Atletico against 2004 UEFA Cup winners Valencia.
Atletico beat Valencia on the away goals rule to progress from the quarter-finals two years ago, but only four players remain who featured in that game, under new coach Diego Simeone.
The Madrid club have strung together nine consecutive wins in Europe and in Radamel Falcao have the tournament's second highest scorer with eight goals.
The Colombia striker top-scored with 17 goals in the competition last year when he guided former club Porto to victory in the final over Braga.
Valencia lie third in La Liga, seven points ahead of eighth-placed Atletico, and are on course to qualify for the Champions League as they did this season.