Tottenham Hotspur exists in a cycle of windows. Windows of opportunity and windows of rebuilding. Opportunity to win things, and periods of reconstructing its core once its best players have been bought away. That’s why every season now for Spurs, currently at the top of such a cycle, feels urgent. It may be a title contender this year, but there are never any guarantees for the next one.

Lately, Tottenham has done a remarkable job of retaining its top talent. The players have bought into manager Mauricio Pochettino and his project. They understand that he has them playing better soccer collectively than the sum of their parts otherwise probably would under most other managers. They thrive in North London, and there are never any guarantees that they would elsewhere. But how long will it last?

Even after Spurs move into their new stadium next season, and their revenue shoots up even further, a wealth gap will likely remain with the Premier League‘s truly big clubs. Chairman Daniel Levy is notoriously tight with the purse strings, and chances are he will never pay the salaries available at Manchester City and United or Chelsea. Which, logically, puts an expiration date on every star player’s tenure with Spurs.

This, as you might have gathered by now, is about Harry Kane. The 24-year-old striker has probably been the best striker in the Premier League since the start of last season — well, since September, because Kane is a famously slow starter and struggles in August. Kane has even slipped into the conversation about whether he is the best striker in the world at the moment for his uncanny scoring ability and all-round play. He finishes, and he creates as well.

In the 2017 calendar year, his 29 goals trail only Lionel Messi in Europe’s five biggest leagues. With eight goals in nine Premier League games so far this season, Kane is likely to breach the 20 league goal barrier for a remarkable fourth year in a row, all before the age of 25. Now there’s talk about Real Madrid coming after him next summer as its latest galáctico signing, the ultimate vindication of your superstardom.

In a sense, Spurs’ ability to retain Kane, who has been at the club since he was 11, although he was sent out on loan four times early in his pro career, is a litmus test. Keeping their best players and building that lavish new stadium are supposed to pave the way for Spurs to ascend from the upper-middle class of English soccer teams into the aristocracy. To contend for prizes every year, rather than a few times a decade.

But in order to accomplish that, they need to keep hold of the Harry Kanes. And they need to figure out how to keep Real from adding him to the list of big stars Spurs sent that way, including Gareth Bale and Luka Modric, who cemented their status as some of the top players of their generation not in North London but in the Spanish capital.

If next season Kane plays in the white of Spurs, rather than that of Real, it will say as much about the club as his loyalty. If the offer is sufficiently big, and the upgrade in title prospects large enough, players will always go in the end.

On Sunday, Kane only added fuel to that fire by scoring twice and adding an assist in Tottenham’s comprehensive 4-1 defeat of Liverpool at Wembley Stadium, its temporary home where the club has struggled to establish the kind of superiority it had at White Hart Lane. It was the first time in 10 games that Spurs had managed to beat Liverpool, whose title hopes are sinking without a trace after a 3-2-4 start. Tottenham, meanwhile, moved into a tie for second place with Manchester United, five points adrift of City.

In just the fifth minute, Kane beat Simon Mignolet to a ball dumped in between them, evaded the goalie and defender Joel Matip and dinked the ball into the empty net.