In 1990, the year Sampras won his first Slam, these were the players around and below is a list of their respective age:
John McEnroe – 1959 (31)
Ivan Lendl – 1960 (30)
Stefan Edberg – 1966 (24)
Boris Becker – 1967 (23)
Michael Stich – 1968 (23)
Jim Courier – 1970 (20)
Andre Agassi – 1970 (20)
Thomas Muster – 1967 (23)
Goran Ivanisevic – 1971 (19)
Pete Sampras – 1971 (19)
Michael Chang – 1972 (18)
For the sole reason that Sampras actually won his first slam in 1990, I should start his era from that year so here we go again:
Australian Open: Ivan Lendl defeated Stefan Edberg
French Open: Andres Gomez Santos defeated Andre Agassi (Michael Chang was the defending Champion at age 17)
Wimbledon: Stefan Edberg defeated Boris Becker
US Open: Pete Sampras defeated Andre Agassi (beat Muster, Lendl, McEnroe and Agassi in succession to claim his first Grand Slam and establish a new era)
The year Federer started out his era (2003), there was only one worthy opponent left and that was Andre Agassi (33) but he was pretty much done by that time, but you can see that he was still a couple of years older than a couple of members in the generation Sampras had to face in his era.
Also, at the start of 00s, Sampras was also challenged with the newcomers like Hewitt, Safin, Roddick and Federer. And Agassi was still around.
This will tell you how much Sampras had to deal with not only during his time but also the beginning and end of his time. And I have yet to mention players like Patrick Rafter, Richard Krajicek, Wayne Ferreira, Alex Corretja, Marcelo Rios, Yevgany Kafelnikov, Petr Korda, Todd Martin, Cedric Pioline, Guy Forget, Tim Henman, Jeff Tarango, Mark Phillippousis, Andrei Medvedev, Alberto Costa, Sergi Bruguera, Greg Rusedski, Vince Spadea, B. Bjorkman, Thomas Enqvist, Arnold Clement, Fabrice Santoro, Thomas Johansson, Karol Kucera etc. The list is countless with really great playres who had the balls to take any of the top players out on any given day. Nowadays, upsets are a rare find.