All the while, the Nylander tots had one thing on their mind.
"Whatever it was, pingpong, knee hockey, we wanted to beat him," William Nylander said.
Because William was 10 at the time, Backstrom often won in whatever they competed at. Still, young William would never give up.
More than a decade later, William Nylander has closed the gap to the point where there is virtually none anymore.
Selected by the Maple Leafs with the No. 8 pick in the 2014 NHL Draft, Nylander is third on Toronto in scoring with 49 points (14 goals, 35 assists) in 66 games. That's three more points than Backstrom, who has 46 points (15 goals, 31 assists) in 63 games.
After the Capitals defeated the Maple Leafs in six games in the Eastern Conference First Round last season, Backstrom and Nylander were teammates with Team Sweden at the 2017 World Hockey Championships, and won a gold medal together.
Even in victory, their competitiveness showed. During an interview with a Swedish television station, the subject of their intense pingpong rivalry came up.
"I kicked his [butt] before at least," Backstrom said.
Replied Nylander: "He thinks he can beat me, but there's no chance."
Chiding aside, Nylander always has viewed Backstrom as a mentor, often watching him play and gaining valuable tips on how to be successful in the NHL.