Matt Tubbs was on target in sunny Sussex as Pompey continued their pre-season programme with a 1-1 draw at Bognor.
The striker completed a flowing attacking move to give the visitors an early advantage against their non-league opponents at Nyewood Lane.
But they were dealt a double blow as Gary Roberts went off injured at half-time before Alfie Rutherford secured a share of the spoils.
Pompey lined up in Cook’s favoured 4-2-3-1 formation and immediately set about trying to pass their way through the Rocks defence.
They were enjoying plenty of possession and Roberts saw a shot deflected inches past the post in the opening stages.
Teenage Blues keeper Alex Bass had been loaned to the hosts and his first piece of action was to claim a Christian Burgess header from the resulting corner.
But the Blues broke the deadlock thanks to a fine flowing move on eight minutes.
Michael Doyle’s incisive pass sent Enda Stevens clear down the right and he squared the ball for TUBBS to roll home.
The striker almost doubled the advantage moments later when he met Gareth Evans’ knock-down at the far post, only to be denied by a last-gasp Craig Robson challenge.
There were further half-chances from both Evans and Tubbs as the visitors continued to dominate as the half progressed.
But Bognor then, out of the blue, created a couple of excellent opportunities, with skipper Jason Prior’s acrobatic bicycle kick narrowly missing the target.
Stuart Green was next to go close, courtesy of a fiercely-struck volley from the edge of the box that crashed against the crossbar.
Bognor Regis 0
Cook made just one change at the start of the second half, with Roberts – who picked up an injury just before the break – making way for Adam McGurk.
Pompey did not look as fluid as they had before the interval, with the chances drying up at both ends.
But Bognor found themselves level on 57 minutes when Rutherford stole the ball from Paul Robinson and coolly stroked the ball past Paul Jones.
The Blues immediately went on the attack, with both Evans and Doyle narrowly failing to find the target.
McGurk had a better opening on 65 minutes, but could only fire straight at Rocks keeper Lyall Beazley after cutting inside from the right.
Goalscorer Tubbs was then withdrawn, with triallist Theo Robinson replacing him in the Pompey attack.
However, it was Doyle who came close to restoring their advantage on 75 minutes with a bending effort that beat Beazley’s dive, but also the post.
The Blues continued to push forward in search of a late winner, but the Rocks were resilient and held on for a draw.
Bognor (4-4-2): Bass (Beazley 46); Crane, Robson, El-Abd, Wollers (Horncastle 70); Parsons (Pearce 56), Green, Thomson (Sanders 52), Tuck (Beck 56); Prior (c) (Rowlatt 76), Dodd (Rutherford 46)
Goals: Rutherford 57
Pompey: Jones; Davies, P.Robinson (c) (Nilsen 86), Burgess (Field 86), Stevens; Atangana, Doyle; Roberts (McGurk 46), Bennett, Evans (Hassan 87); Tubbs (T.Robinson 66)
Goals: Tubbs 8
Subs not used: Poke, Haunstrup, Close