With three warm-up matches left for Joe Schmidt to decide on his final 31-man Ireland squad for the World Cup, and now 40 players left in contention, the competition is intensifying for a spot on the plane to Japan.

After a warm-weather training camp in Portugal, the Irish will take on England at Twickenham with a double header against Wales to follow.

And while there is plenty of interest in who will get the final places in the squad, just as intriguing is what Schmidt will go for as his first-choice XV.

Perhaps the biggest call of the lot will be in the midfield, with Bundee Aki and Robbie Henshaw having monopolised the inside centre spot over the last three years.

Respectively Aki and Henshaw have started 17 and nine matches for Ireland over the last three years, making up 26 of the 33 Tests played in that time.

While both are capable of playing elsewhere, including together, it may come down to a straight decision between them to partner Garry Ringrose, the only player to start more regularly in the centres for Ireland in that period.

With that in mind, it is revealing to look at their respective performances for Connacht and Leinster, where the two have been so influential.

Of course Henshaw started his career in Galway, and played alongside Aki in the midfield in their 2016 title run.

A look at their efforts last season and it is clear they fulfil similar, if not identical roles for their provinces.

Despite being slightly smaller in terms of stature, Aki still packs an almighty punch and is often used to open up space for those outside him.

Averaging just over three metres per carry, he has a slight edge on Henshaw, although both are invaluable in the role.

Defensively, both rate very highly, with a tackle success in excess of 85 per cent, although in this category it is Henshaw who has the narrow advantage.

The main disparity between the two is in the turnover battle, with Aki recording ten last season to just four from Henshaw. Even bearing in mind the extra minutes played by Aki, he still averages a turnover every 70 minutes, to one every 145 for Henshaw.

That of course can be in large part to the tactics employed by Connacht and Leinster, although Aki’s stockier frame may also lend itself to jackaling a little more than his Leinster counterpart.

One area where Henshaw will have the advantage is his relationship with Ringrose, his Leinster teammate with whom he has built a strong rapport.

However since 2016, the trio have all shown they are capable of stepping up to the highest level, giving Schmidt the perfect headache ahead of Japan.