Three key questions ahead of Middlesbrough's meeting with Plymouth Argyle as Neil Warnock assesses his squad

Neil Warnock’s side will play their first friendly of the summer on Tuesday when they take on League One outfit Plymouth Argyle (1pm kick-off).

Boro’s squad remains thin due to the club’s lack of signings, so it will be interesting to see which players feature during pre-season.

Ahead of the match against The Pilgrims, here are three important things to look out for.

Who will start at centre-back?

It sounds a simple one yet Boro’s lack of options at the heart of defence is alarming.

In the last few months, George Friend, Ryan Shotton, Daniel Ayala and Harold Moukoudi have all left the Riverside, and replacements have been hard to find.

Former QPR captain Grant Hall joined the club on a free transfer and looks like a good piece of business.

Yet, with less than two weeks to go until the start of the new campaign, Hall and Dael Fry are Boro’s only centre-back options with significant Championship experience.

Sam Stubbs appears to be the next player in the pecking order following loan spells at SPL side Hamilton and with top-flight Dutch club ADO Den Haag last term.

The 21-year-old will now feel he’s ready to test himself in the Championship and surely won’t get a better opportunity to prove himself.

Teenager Nathan Wood, 18, made his league debut last season and will be looking to kick on this year, yet it feels like the youngster would be better off going out on loan.

What formation will Boro play?

Last season Boro switched between a back four and a back three with wing-backs.

Ideally Warnock wants to play with a 4-3-3 system, yet a lack of natural wingers in the squad made it tricky last term.

It’s still possible to play the manager’s favoured system, with Marcus Tavernier, Marvin Johnson, Djed Spence and Hayden Coulson providing options on the flanks.

The dilemma is that Johnson or Coulson will probably be needed to play at left-back while Spence is naturally a right-back.

There should also be an opportunity for Marcus Browne who has returned from a loan spell at Oxford and will be keen to impress.

Boro’s aforementioned shortage of centre-backs may make it difficult to play with a back three, yet it should be remembered that Anfernee Dijksteel was used as a right-sided centre-back last season.

Who will captain the side?

Warnock regularly commented on Boro’s lack of leaders last season – yet the squad has even less experience than it did a few months ago.

Last season’s captain, Friend, has moved to Birmingham while fellow defender Shotton was also one of the more vocal characters.

It begs the question who will wear the captain’s armband this campaign?

Jonny Howson is a player who leads by example but has admitted he isn’t the loudest voice.

Or could Warnock make Hall his new skipper – a role he occupied at QPR? Time will tell.