Dwayne Bravo's career-best T20 International figures of four for 19 led the West Indies to a successful defence of a modest total as the home side pulled off a series-levelling 21-run victory over South Africa in the fourth match of the five-game series on Thursday.

Set a target of 168 after captain Kieron Pollard belted an unbeaten 51 off 25 balls with five sixes and two fours to lift the West Indies to 167 for six, the Proteas relied heavily on the consistent Quinton de Kock in their quest to clinch the contest ahead of the final match on Saturday at the same venue.

However his dismissal to Bravo for a top score of 60 at the start of the 18th over was the death-knell for the visitors' effort.

The ebullient all-rounder added two more victims in what was the final over of his allottment to ensure that the last encounter of this South African tour will have the feel of a final.

South Africa finished on 146 for nine and will be concerned about the fitness of key pacer Anrich Nortje, who took a painful blow on the left knee in the midst of Pollard's late assault.

Pollard's innings and an unbroken seventh-wicket partnership of 66 with Fabien Allen (19 not out) were critical in giving the Caribbean side a fighting chance after they were put in to bat for the first time in the series.

West Indies again struggled against the spin of Tabraiz Shamsi and George Linde with Shamsi equalling his personal-best economical figures of two for 13 from the third match in claiming the important wickets of Nicholas Pooran and Andre Russell.

Linde was no less effective, his four overs costing 16 runs while he had considerable cause for celebration in claiming the wickets of Lendl Simmons and Shimron Hetmyer.

Simmons got his team off to a blistering start, taking 20 runs off the opening over of the match from part-time spinner Aiden Markram. 

He set the early pace with an innings of 47. 

However the introduction of the two specialist slow bowlers put an immediate brake on the scoring and then wickets started falling at regular intervals.

When Russell's top-edged sweep to Shamsi was taken at short fine-leg the West Indies were labouring at 101 for six in the 16th over.

It took the aggression of Pollard, who helped to take 25 runs off the penultimate over of the innings from Kagiso Rabada, and the support of Allen to get the World T20 champions up to a score on par with South Africa's three totals batting first earlier in the series.

"I was just happy to be there at the end to make an important contribution," said the West Indies captain.

"I must commend Bravo's effort with the ball as well, especially as he has faced a lot of unnecessary criticism with people saying he is too old now to be a productive member of this team."

West Indies were hampered in the field when frontline spinner Fabian Allen injured his right shoulder attempting a boundary save early on.

By then though the senior players were already making significant contributions as Chris Gayle, back in the team for this match, had de Kock's opening partner Reeza Hendricks stumped with the first ball he bowled.

Andre Russell, notwithstanding the constant challenge with knee ailments, took two wickets and Pollard himself joined in the wicket-taking by having Rassie van der Dussen caught behind in the highlight of a four-over spell where he conceded 24 runs.

Scoreboard

Scoreboard of the 4th T20 International of the five-match series between the West Indies and South Africa at the National Cricket Stadium in Grenada on Thursday:

West Indies Innings

L. Simmons lbw b Linde 47

E. Lewis c Markram b Nortje 7

C. Gayle c de Kock b Rabada 5

S. Hetmyer c de Kock b Linde 7

N. Pooran c van der Dussen b Shamsi 16

K. Pollard not out 51

A. Russell c Nortje b Shamsi 9

F. Allen not out 19

Extras (b1, lb1, w4) 6

Total (20 overs, 6 wkts) 167

Did not bat: D. Bravo, O. McCoy, F. Edwards

Fall of wickets:  1-27 (Lewis), 2-32 (Gayle), 63-3 (Hetmyer), 4-70 (Simmons), 5-89 (Pooran), 6-101 (Russell)

Bowling: Markram 1-0-20-0, Ngidi 4-0-48-0 (2w), Nortje 4-0-32-1, Rabada 3-0-36-1 (1w), Linde 4-0-16-2, Shamsi 4-0-13-2 (1w)

South Africa Innings

Q. de Kock c Simmons b Bravo 60

R. Hendricks st Pooran b Gayle 2

T. Bavuma lbw b McCoy 7

A. Markram b Russell 20

R. van der Dussen c Pooran b Pollard 6

D. Miller c Gayle b Russell 12

G. Linde c Simmons b Bravo 6

K. Rabada not out 16

T. Shamsi c Gayle b Bravo 0

L. Ngidi c Simmons b Bravo 0

A. Nortje not out 4

Extras (b5, lb3, w4, nb1) 13

Total (20 overs, 9 wkts) 146

Fall of wickets: 1-8 (Hendricks), 2-36 (Bavuma), 3-62 (Markram), 5-94 (Miller), 6-110 (Linde), 7-126 (de Kock), 8-126 (Shamsi), 9-127 (Ngidi)

Bowling: Edwards 2-0-21-0, Gayle 2-0-11-1 (1w), McCoy 4-0-33-1 (2w, 1nb), Russell 4-0-30-2 (1w), Bravo 4-0-19-4, Pollard 4-0-24-1

Result: West Indies won by 21 runs

Series: 2-2

Toss: South Africa

Umpires: Leslie Reifer (WIS), Patrick Gustard (WIS)

Match Referee: Richie Richardson (WIS)