Portisch from Hungary and Smyslov from Soviet Union had shared 7th place at the Palma de Mallorca Interzonal (1970) and FIDE wanted a no. 1 reserve player should any of the eight Candidates players (Tigran Petrosian, Viktor Korchnoi and the top six finishers in Palma) withdraw or be unable to attend. The players met in hotel Neptun, Portoroz to settle the matters. The organizers were nervous because Portisch arrived extremely late, by car from Hungary, together with his second Istvan Csom. They had visited Ljubljana along the way, but the match could start as scheduled. Smyslov was assisted by Paul Keres. The match was sponsored by the Piran Institute for Promotion of Tourism. The chief arbiter was Vasja Pirc. After a draw in the first game the players won one game each (with the black pieces). Then followed two draws. The last game was a draw in 21 moves. Smyslov had to win, but he was probably aware that the eight official candidates were perfectly well.

Portoroz, Yugoslavia (Slovenia), 30 March - 7 April 1971

Portisch  ½ 1 0 ½ ½ ½  3
Smyslov   ½ 0 1 ½ ½ ½  3

What kind of present are you expecting for your thirty-fourth birthday? — In practice, there is not much point in fighting in Portoroz. It is unlikely that any of the eight grandmasters would cancel the competition. I've played with Smyslov many times, but I haven't won against him yet. He has a fantastically sophisticated sense of chess, he rarely makes mistakes. I think the best birthday present for me will be to have an enjoyable and educational competition with one of the best chess players in the world. Even a draw would be considered a success...! (Portisch in Népsport)

A victory even if it doesn't have any practical significance. It is about my final match against Smyslov, which we fought for the reserve place ... this match would only make sense if one of the world champion candidates stepped down. However, the probability of this is low. (Unfortunately...) Still, I considered this task important in my chess career, because with two lost matches behind me (against Tál and Larsen) I wanted to prove myself. Maybe many people now think that I can't compare the fifty-year-old Smyslov to Larsen, who is in the prime of his life. It is true that Larsen is stronger now, but Smyslov was world champion 16 years ago, and if he was still constantly playing in his then form, he would hardly have had to compete with me! But the fact that his playing power has not worn out too much is also proven by his recent results. It is enough to refer to last year's Soviet Union World Team meeting, where in the last game of the match he put his much younger opponent, the Icelander Olafsson, on his two shoulders, and with this one point difference, he secured the final victory for his team. I've played with my great opponent in several tournaments, but I've never managed to beat him ... We finished tied in Palma de Mallorca and the Berger-Sonneborn calculation favored me. Thus, according to the rules, the tie-breaking match was in my favor in the event of a tie. So my goal was primarily to keep this advantage. Even if I can't be satisfied with the quality of the games (this is a feature of almost all matches), I did well in terms of competitive tactics. For a long time and many times, one has blamed me that I have an aversion to psychological warfare. Well, this was my number one weapon in this match. I consciously and at all costs strove for complications, because few can compete with Smyslov in the clean, calm positional game. It is true that in the third game I overshot the target and lost the advantage I had gained, but this tactic was of great importance in the last round. Previously, I could have decided the match in the fifth game, but I alienated the honorable pawn (against two pawns). In the last game, Smyslov was clear in vain, because he again had to play against one of the sharpest defenses, the Sicilian defense. After the ordeal of the previous day, he no longer dared to risk losing and settled for a draw. (Portisch in Képes Sport)

Sources (not seen: Šahovski glasnik 1971/8 and Mat 1971/7)

Népsport, 28 March 1971, p. 5 (https://adt.arcanum.com/en/view/Nem...)
Борба (Borba), 30 March 1971, p. 11 (https://istorijskenovine.unilib.rs/...)
Борба (Borba), 1 April 1971, p. 13 (https://istorijskenovine.unilib.rs/...), etc.
Tidskrift för Schack, May 1971, p. 107 (https://tfsarkiv.schack.se/pdf/1971...)
Večiti Šah (Perpetual Check) website (http://www.perpetualcheck.com/show/...)
Smyslov in Jaque 4, 1 July 1971, pp. 24-25 (http://www.bartelski.pl/olimpbase/l...)
Lajos Portisch in Képes Sport, 27 April 1971, p. 21 (https://adt.arcanum.com/en/view/Kep...)

Original collection: Game Collection: Portoroz Candidates Reserve Playoff 1971 by User: Tabanus. Game dates in Večiti Šah (March 30, 31, April 2, 3, 5, 7) do not contradict Борба (Borba) and Hungarian newspapers.