"The biggest opportunity we've had - or maybe ever will have - to show the sport to new audiences."
Liam Carroll, head coach of the Great Britain baseball team, has no doubt about the importance of the London Series weekend, which provided a landmark game in this storied rivalry.
For two nights, the famous West Ham song 'I'm forever blowing bubbles' was replaced by the baseball anthem 'Take me out to the ball game' as London Stadium played host to one of sport's most iconic rivalries.
In the blue corner, the New York Yankees. In the red corner, the Boston Red Sox.
The occasion? The first regular-season Major League Baseball (MLB) games to be played in Europe.
In the build-up to the matches - played in front of two sell-out crowds - BBC Get Inspired spoke to Carroll, the MLB, and a die-hard baseball fan to explore what impact the London Series could have on the sport's popularity in the UK.
Following the NFL blueprint in Europe
This is not the first time MLB matches have been played outside of the United States or Canada.
The first took place in Mexico in 1996 as the San Diego Padres took on the New York Mets. There have also been games hosted in Japan, Puerto Rico and, most recently in 2014, Australia.
All have helped grow interest in the game in those regions.
And Charlie Hill, the MLB's vice-president of international strategy, says "now is the time" to shift the focus to Europe.
"We want more people aware, playing and watching our sport," he says.
"How you choose to engage with baseball is up to you, whether it's wearing a baseball cap with a team name on, picking up a bat, or watching the London Series on the television."
The National Football League (NFL) has held regular games in the United Kingdom - to sell-out crowds - since 2007. That is something Hill wants the MLB to learn from.
"Most sports have conversations about internationalising," he says. "Like soccer playing friendly games in Asia and the USA - they want to grow their footprint.
"When it comes to the UK and you look at what other US sports have done, inevitably you look at the NFL.
"But these are long-term projects. You don't transform a marketplace overnight."
Will British fans like the 'Americanism' of baseball?
More than 70% of tickets for the London Series have been sold to people living in Britain.
The MLB also put on a three-day festival in east London at which fans could immerse themselves in American culture, food and live music.
John McGee, from the podcast Bat Flips and Nerds - a British take on Baseball, believes the "Americanism" of baseball may put off some British sports fans, while others may embrace it.
"I like American culture - music and films - but it wasn't the rooting, tooting all-American pastime that I was drawn to, but many people in the UK will be," he added.
"I think they will go for that in the London Series - introduce a slice of good old America."
But we have cricket...
Though cricket is the primary 'bat-and-ball' game in the UK, Carroll says it is a "cop out" to suggest baseball cannot compete.
"The two sports are similar; I'd say they're cousins and we can co-exist," says Carroll, who has been in charge of the national team since 2015.
"I don't think we'll ever be as big as cricket, but there are enough participants to go around."
Carroll says baseball needs to be creative to grow participation numbers - including encouraging club cricketers to give the sport a go.
"Whether it is to improve their fielding in cricket or they want to leave cricket and try baseball, we're 100% open to that," he says.
Is baseball too difficult to understand?
McGee acknowledges baseball can be a "complicated sport" for newcomers to understand, which could "make it difficult for British fans to reconcile with".
"On its base level it may be a simple sport, but the difference between a ball and a strike, explaining what a strike zone is and why it's called that - it's a bit like explaining why the fielding position silly mid-off is called what it is in cricket," he says.
"Once you get into the nuances of how baseball works, it gets complicated.
"There's more to it than just popcorn, hotdogs and having a good time. A lot of people don't have the patience to get into cricket and I think baseball is the same."
The MLB introduced several initiatives and adaptations of the sport to welcome new players during the London Series weekend, including the showcase final of Softball60 - a simplified version of softball taking place in urban London areas - and the Play Ball Park activities introducing schoolchildren to baseball.
Carroll says one of the aims of GB Baseball is to have a "born and raised" British player sign for an MLB club, and cites the example of German Max Kepler.
He made his MLB debut in 2015 and recently signed a five-year contract extension worth £35m.
"To have that success for a British player would be a massive boost for the sport in this country and would give us media coverage," he says.
For now, Carroll is excited the two biggest MLB sides are showcasing their skills in London, with a two-game series between St Louis Cardinals and Chicago Cubs to follow next July.
"If this can't help us increase participation then I don't know what will," he says.