On this day in 1999, Manchester United took the second step towards their treble by beating Newcastle 2-0 in the FA Cup final. We continue our 20th anniversary coverage with a look at how Teddy Sheringham overcame a frustrating season to play a key role in their success. A season of frustrationSheringham is regarded as a key figure in Manchester United’s treble because of his FA Cup final goal against Newcastle and his Champions League final equaliser against Bayern Munich in Barcelona a few days later. But it is often overlooked that up until then he had been a peripheral figure.The forward had been a regular starter in the previous season, scoring 14 goals in 42 games in all competitions following his move from Tottenham, but Dwight Yorke’s arrival from Aston Villa a year later changed everything. Yorke became Sir Alex Ferguson’s first-choice partner for Andy Cole, pushing a disgruntled Sheringham down the pecking order. “For Manchester United, it was a fantastic season,” Sheringham said in a Sky Sports documentary. “For me, personally, up until the last two weeks of the season, I was very frustrated. I lost my place to Yorkey, first of all, then got a couple of…