It was always going to be Boro's toughest test of their pre-season schedule to date and so it proved against a Betis side managed by Gus Poyet.
For long periods of the first half in the Marbella Stadium Boro were penned back and although defending well they found it difficult to break free from a determined stranglehold.
For all that, there were few chances in an opening 45 minutes that was for extended passages another extension of a training ground exercise, admittedly played at a slightly higher tempo.
There was an early flurry when Cejudo went through on goal but Dimitrios Konstantopoulos made himself big and saved well.
The opening goal came after 26 minutes when Dani made an unchecked run at close quarters behind the Boro back line, was picked out with a clever pass and tucked home from a narrow angle.
There was almost an equaliser just four minutes later but a David Nugent shot struck a post.
Approaching half-time the game briefly threatened to boil over when three players were booked. Marten de Roon for a foul and Petros for his reaction off the ball went into the notebook just ahead of Nathan McGinley for a high challenge.
Boro were more effective after the break and had the ball in the net though Viktor Fischer, but he had strayed offside when picking up a Jordan Rhodes flick on.
Julien De Sart tried to feed Rhodes with a searching ball but the keeper reacted quickly.
Strong work from Adam Jackson repelled what was for Betis a somewhat rare foray in the second half. A mistake and an unlucky bounce in Boro's penalty area led to a second for Real Betis when Ruben rifled home form 12 yards.
It took Boro a minute to pull one back as Jordan Rhodes rose to head home from close range when meeting a right wing cross from Cristhian Stuani.
Gaston Ramirez returned to the Boro fold ten minutes from the end after permission was given just before kick-off to allow him to take part.
He hasn't finalised a deal yet, but is training with Boro in Marbella while paperwork is concluded on what will be a three-year deal.
With two minutes of normal time remaining Emilio Nsue charged into the Betis box and fed the Uruguayan, but an attempt at a quick turn was thwarted and there was to be no goalscoring return.
Boro first half:
Konstantopoulos; Barragan, McGinley, Morris, Gibson, De Roon, Reach, Clayton, Nugent, Downing, De Pena.
Boro second half:
Mejias; Nsue, Baptiste, Jackson, Friend, Stuani, Reach (Ramierez 80), Forshaw, Fischer, De Sart, Rhodes.