A No, it wasn't. I can find two previous occasions where this has happened. On March 13th 1920 Scotland beat Ireland 3-0 at Celtic Park. Scottish keeper Kenny Campbell and his Irish counterpart Elisha Scott were both with Liverpool at the time. Campbell had been at Anfield since 1911, Scott a year later. But for war they would surely have faced each other more than once.
Campbell was the first choice at Anfield, playing 33 League games to Scott's nine that season. The Scot signed for Partick Thistle a month after this game.
The second occasion was on October 2nd 1965 in Belfast when Northern Ireland beat Scotland 3-2. Pat Jennings kept goal for the home team and Spurs team-mate Bill Brown was the Scotland keeper. Jennings was in the early stages of his long career and Brown was nearing the end of his time at White Hart Lane.
This pair were scrapping for the first team shirt at Tottenham. Brown played in 20 League matches that term and Jennings 22.
I've seen publications which claim opposing goalkeepers David Harvey and Gary Sprake were both with Leeds United when Scotland beat Wales 2-0 at Hampden on May 14th 1974. But although they both started the season together at Elland Road, Sprake signed for Birmingham City in October 1973.
A The goals came from Billy Hainey and a Finn Seemann penalty in the 2-1 win in the Nou Camp on October 25th 1966. When United won 2-0 at Tannadice on November 16th thanks to strikes from Hainey and Ian Mitchell they became the first team other than Real Madrid to win both legs of a European tie against Barca.
Remarkably, this was Dundee United's first appearance in European competition.
There have been other occasions - particularly in the Glasgow Cup - when games have been decided by the toss of a coin or on corner kicks.
A Billy Brown started out with Musselburgh Athletic. His first senior club was Hull City in 1969. He didn't make any first team appearances there and returned to Scotland to sign for Motherwell at the start of 1970-71. A half-back/inside-forward, he wasn't a regular at Fir Park, making just nine league starts in three seasons. He also turned out eight times in the League Cup (three as substitute).
John Litster's record of post-war players lists him as appearing twice in the Texaco Cup in 1971-72 but Rothman's Football Yearbook only credits him with one appearance.
He scored once for Motherwell - and that was in an 8-3 away defeat by Partick Thistle in December 1971.
He moved on to Raith Rovers at the onset of 1973-74 and enjoyed greater success there. He made 91 league appearances, scoring five times, twenty League Cup appearances, seven in the Scottish Cup, one in the Drybrough Cup and five in the 1976 Spring Cup. He didn't score in any of those competitions.
The highlight of his playing career came in 1976 when Raith Rovers won promotion to the First Division. His final appearance was as a substitute at Stark's Park in February 1978 in a League game v Meadowbank Thistle.
All told that makes 142/143 appearances (a question mark remains over the Texaco Cup) in recognised first-class competitions and six goals scored.
He first teamed up with childhood friend Jim Jefferies in management at Gala Fairydean and the pair have continued to operate in tandem at Berwick, Falkirk, Hearts, Bradford City and Kilmarnock.
Jenkins, Gray, Shaw, Little, Young, Symon, Waddell, Duncanson, Gillick, Marshall & Johnstone.
If anyone out there has the Celtic team and/or the scorer we'd like to hear from you.
A The youngest captain was also the youngest player - John Lambie of Queen's Park, in 1886. See the answer to Robert Houston's question here (left-hand column, second question).