Help making fights longer/harder

[DragonKnight]

Running a different concept than normal, and two of my players frequent these forums, so if they stumble across this, I hope they don't read too far, lol.

Basically, putting them in a tournament style deal, making them fight one on one(not each other obviously). This could be a stupid idea, or could be good. They like the idea if anything.

I want the fights to be hard, but winnable, I want my party to win, not die.

One is a human - Warblade10, the other is a human druid10, a custom race Hexblade9/Rogue1, and a wood elf Scout10. I have an NPC to give them a five man team if needed.

Basically, I'm wanting input for making the fights last longer. Other than just giving the enemies a huge hp pool and toning their damage down. Only problem with that, if they're doing less damage, the party members are mocking the enemies the entire time for being 'weak'. I want them to feel like they're earning their victories. Any input would be appreciated.

[Zhalath]

Well, make sure the arena opponents have actual strategies. A guy who just charges and attacks will get eaten by your player, because that's what they will probably do too. Have your NPC opponents use stuff like Combat Expertise or other feats to flit around or avoid taking damage. If any of your PCs get too confident, and start taunting the opponent, teach them a lesson about humility(you're the DM, you can fudge dice rolls in your favor).
Think about your PCs strategies, and think of ways to counter that. Make them think in a new way.

[Olo Demonsbane]

Do different fights besides 1 vs 1 or 5 vs 5 or whatever.

Favorite arena fights:
The Brawl: No one is given weapons or armor.
The Siege: One (smaller) team is given the task of defending a structure.
Hide and Seek: Because of the terrain, it can be near impossible to find those stupid rouges...
True Hide and Seek: All characters/monsters are blindfolded.

In short: Make the terrain interesting and introduce unexpected twists.

[Sstoopidtallkid]

Arcane Casters can normally Fly, with miss chance, and have abilities that teleport them away to avoid attacks. A Warlock for a later fight, described as a caster who has been through twice as many fights as them already that day, should scare the crud out of them. Especially if he has Eldrich Glaive for massive damage.

[streakster]

Hit their weak points - introduce the warblade to the invisible ranged attacker, the scout to a movement denial specialist, maybe immune to skirmish as well, and the hexblade to - well - anything really. Anything at all. Poor guy. And the druid - ummm - yeah. Something physically tough and immune to magic, mayhaps? Or just another druid.

yesiamtotallymaligningthehexbladehereiknowhesreall ynotthatbadOKitwasforeffectnowstopbugginme