O’brien is key to striking balance in the back row

It is vital for Lions to get the right combination alongside Faletau – and Irishman is a perfect fit

One of the most vital decisions Warren Gatland must get right before the start of the Test series is the balance in his back row. On only one occasion in the opening four games has it worked, but finding that perfect combination is one of the most elusive things in rugby.

Having played in the back row for my entire career, this is what I believe you are looking for in each position.

No 6 Blindside flanker

You need a grafter, a serious ball-carrier who can add bite and nastiness, while preferably offering a line-out option, which makes Peter O’mahony stand out. So this is a position for an allrounder, a breakdown king and someone capable of a little X-factor.

My perfect blindside flanker would be New Zealand’s likely Test six, Jerome Kaino. He can ask questions of a defence, rarely misses a tackle and has skilful hands, which makes him influential in the line-out.

No 7 Openside flanker

The traditional openside is a Richie Mccaw-type, a breakdown specialist who lives off turnovers. I spent my whole career in this position, and I can tell you that our definition of an openside is definitely changing! Nowadays everyone is capable of stealing the ball, so your seven must be a calm and collected type who knows when to commit and when to stand off, while providing enough energy to inspire the team. I always considered my style of play to be very similar to Michael Hooper, the Australia flanker, who never stops moving.

No 8

Your enforcer, the player who sends a shiver down opposition spines. They have to create the platform for the backs to play off, so you need a hard runner who will lead the team by creating momentum. The No 8 is your go-to guy, the person you know will make ground from a standing start. Billy Vunipola is becoming almost the perfect No8, and it is such a shame that injury means we will not see him going up against Kieran Read on this tour.

The perfect back row, then, should combine carrying ability, breakdown nous, pace, a line-out option and good hands. When you find a combination that works, it is glorious. When England won the Women’s World Cup in 2014, we had a brilliant combination in blindside flanker Marlie Packer, No8 Sarah Hunter, and myself at openside. We complemented each other perfectly.

Every back-row player on the tour will know their strengths and have an idea of who will compliment them. For example, I am sure C J Stander will be thinking about his carrying game matching up alongside Justin Tipuric’s pace, or Ross Moriarty’s big hits combined with Sean O’brien’s cleverness at the breakdown. You start to make alliances thinking it may help both of you get in the team.

You also know who you do not want to play alongside, which is why I was surprised Gatland went for James Haskell, Sam Warburton and Stander against the Highlanders. None of them had the pace to match the hosts and they were crying out for a different type of player – a Tipuric, perhaps – to give them another option.

At present the only certainty is that Taulupe Faletau will start at No 8. He is the closest they have to Vunipola and is in excellent form.

Warburton would be next on my teamsheet, but at six rather than seven. He is getting better with every game and his leadership will be important. The openside spot is the most difficult of all, but I would go for O’brien. He was brilliant against the Crusaders and, by picking him and Faletau, you have two big ball-carriers to draw in defenders, while he and Warburton would bring energy and are breakdown specialists.

That is a back three unit which can take on the All Blacks. If we struggle in the back row, we will be second best at the breakdown, will fail to get good ball to our playmakers and will lack any real bite in our game. It is vital Gatland gets his decision right.